14208b0ec5
Pull cgroup updates from Tejun Heo: "A lot of activities on cgroup side. Heavy restructuring including locking simplification took place to improve the code base and enable implementation of the unified hierarchy, which currently exists behind a __DEVEL__ mount option. The core support is mostly complete but individual controllers need further work. To explain the design and rationales of the the unified hierarchy Documentation/cgroups/unified-hierarchy.txt is added. Another notable change is css (cgroup_subsys_state - what each controller uses to identify and interact with a cgroup) iteration update. This is part of continuing updates on css object lifetime and visibility. cgroup started with reference count draining on removal way back and is now reaching a point where csses behave and are iterated like normal refcnted objects albeit with some complexities to allow distinguishing the state where they're being deleted. The css iteration update isn't taken advantage of yet but is planned to be used to simplify memcg significantly" * 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (77 commits) cgroup: disallow disabled controllers on the default hierarchy cgroup: don't destroy the default root cgroup: disallow debug controller on the default hierarchy cgroup: clean up MAINTAINERS entries cgroup: implement css_tryget() device_cgroup: use css_has_online_children() instead of has_children() cgroup: convert cgroup_has_live_children() into css_has_online_children() cgroup: use CSS_ONLINE instead of CGRP_DEAD cgroup: iterate cgroup_subsys_states directly cgroup: introduce CSS_RELEASED and reduce css iteration fallback window cgroup: move cgroup->serial_nr into cgroup_subsys_state cgroup: link all cgroup_subsys_states in their sibling lists cgroup: move cgroup->sibling and ->children into cgroup_subsys_state cgroup: remove cgroup->parent device_cgroup: remove direct access to cgroup->children memcg: update memcg_has_children() to use css_next_child() memcg: remove tasks/children test from mem_cgroup_force_empty() cgroup: remove css_parent() cgroup: skip refcnting on normal root csses and cgrp_dfl_root self css cgroup: use cgroup->self.refcnt for cgroup refcnting ...
1696 lines
46 KiB
C
1696 lines
46 KiB
C
/*
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* Interface for controlling IO bandwidth on a request queue
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*
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* Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/blktrace_api.h>
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#include "blk-cgroup.h"
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#include "blk.h"
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/* Max dispatch from a group in 1 round */
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static int throtl_grp_quantum = 8;
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/* Total max dispatch from all groups in one round */
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static int throtl_quantum = 32;
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/* Throttling is performed over 100ms slice and after that slice is renewed */
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static unsigned long throtl_slice = HZ/10; /* 100 ms */
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static struct blkcg_policy blkcg_policy_throtl;
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/* A workqueue to queue throttle related work */
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static struct workqueue_struct *kthrotld_workqueue;
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/*
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* To implement hierarchical throttling, throtl_grps form a tree and bios
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* are dispatched upwards level by level until they reach the top and get
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* issued. When dispatching bios from the children and local group at each
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* level, if the bios are dispatched into a single bio_list, there's a risk
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* of a local or child group which can queue many bios at once filling up
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* the list starving others.
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*
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* To avoid such starvation, dispatched bios are queued separately
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* according to where they came from. When they are again dispatched to
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* the parent, they're popped in round-robin order so that no single source
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* hogs the dispatch window.
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*
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* throtl_qnode is used to keep the queued bios separated by their sources.
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* Bios are queued to throtl_qnode which in turn is queued to
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* throtl_service_queue and then dispatched in round-robin order.
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*
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* It's also used to track the reference counts on blkg's. A qnode always
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* belongs to a throtl_grp and gets queued on itself or the parent, so
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* incrementing the reference of the associated throtl_grp when a qnode is
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* queued and decrementing when dequeued is enough to keep the whole blkg
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* tree pinned while bios are in flight.
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*/
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struct throtl_qnode {
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struct list_head node; /* service_queue->queued[] */
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struct bio_list bios; /* queued bios */
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struct throtl_grp *tg; /* tg this qnode belongs to */
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};
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struct throtl_service_queue {
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struct throtl_service_queue *parent_sq; /* the parent service_queue */
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/*
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* Bios queued directly to this service_queue or dispatched from
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* children throtl_grp's.
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*/
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struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */
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unsigned int nr_queued[2]; /* number of queued bios */
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/*
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* RB tree of active children throtl_grp's, which are sorted by
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* their ->disptime.
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*/
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struct rb_root pending_tree; /* RB tree of active tgs */
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struct rb_node *first_pending; /* first node in the tree */
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unsigned int nr_pending; /* # queued in the tree */
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unsigned long first_pending_disptime; /* disptime of the first tg */
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struct timer_list pending_timer; /* fires on first_pending_disptime */
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};
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enum tg_state_flags {
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THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
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THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
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};
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#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
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/* Per-cpu group stats */
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struct tg_stats_cpu {
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/* total bytes transferred */
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struct blkg_rwstat service_bytes;
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/* total IOs serviced, post merge */
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struct blkg_rwstat serviced;
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};
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struct throtl_grp {
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/* must be the first member */
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struct blkg_policy_data pd;
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/* active throtl group service_queue member */
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struct rb_node rb_node;
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/* throtl_data this group belongs to */
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struct throtl_data *td;
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/* this group's service queue */
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struct throtl_service_queue service_queue;
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/*
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* qnode_on_self is used when bios are directly queued to this
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* throtl_grp so that local bios compete fairly with bios
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* dispatched from children. qnode_on_parent is used when bios are
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* dispatched from this throtl_grp into its parent and will compete
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* with the sibling qnode_on_parents and the parent's
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* qnode_on_self.
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*/
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struct throtl_qnode qnode_on_self[2];
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struct throtl_qnode qnode_on_parent[2];
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/*
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* Dispatch time in jiffies. This is the estimated time when group
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* will unthrottle and is ready to dispatch more bio. It is used as
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* key to sort active groups in service tree.
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*/
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unsigned long disptime;
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unsigned int flags;
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/* are there any throtl rules between this group and td? */
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bool has_rules[2];
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/* bytes per second rate limits */
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uint64_t bps[2];
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/* IOPS limits */
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unsigned int iops[2];
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/* Number of bytes disptached in current slice */
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uint64_t bytes_disp[2];
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/* Number of bio's dispatched in current slice */
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unsigned int io_disp[2];
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/* When did we start a new slice */
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unsigned long slice_start[2];
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unsigned long slice_end[2];
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/* Per cpu stats pointer */
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struct tg_stats_cpu __percpu *stats_cpu;
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/* List of tgs waiting for per cpu stats memory to be allocated */
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struct list_head stats_alloc_node;
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};
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struct throtl_data
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{
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/* service tree for active throtl groups */
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struct throtl_service_queue service_queue;
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struct request_queue *queue;
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/* Total Number of queued bios on READ and WRITE lists */
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unsigned int nr_queued[2];
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/*
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* number of total undestroyed groups
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*/
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unsigned int nr_undestroyed_grps;
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/* Work for dispatching throttled bios */
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struct work_struct dispatch_work;
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};
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/* list and work item to allocate percpu group stats */
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static DEFINE_SPINLOCK(tg_stats_alloc_lock);
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static LIST_HEAD(tg_stats_alloc_list);
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static void tg_stats_alloc_fn(struct work_struct *);
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static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
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static void throtl_pending_timer_fn(unsigned long arg);
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static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
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{
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return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
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}
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static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
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{
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return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
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}
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static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
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{
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return pd_to_blkg(&tg->pd);
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}
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static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
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{
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return blkg_to_tg(td->queue->root_blkg);
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}
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/**
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* sq_to_tg - return the throl_grp the specified service queue belongs to
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* @sq: the throtl_service_queue of interest
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*
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* Return the throtl_grp @sq belongs to. If @sq is the top-level one
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* embedded in throtl_data, %NULL is returned.
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*/
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static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq)
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{
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if (sq && sq->parent_sq)
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return container_of(sq, struct throtl_grp, service_queue);
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else
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return NULL;
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}
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/**
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* sq_to_td - return throtl_data the specified service queue belongs to
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* @sq: the throtl_service_queue of interest
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*
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* A service_queue can be embeded in either a throtl_grp or throtl_data.
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* Determine the associated throtl_data accordingly and return it.
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*/
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static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)
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{
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struct throtl_grp *tg = sq_to_tg(sq);
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if (tg)
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return tg->td;
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else
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return container_of(sq, struct throtl_data, service_queue);
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}
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/**
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* throtl_log - log debug message via blktrace
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* @sq: the service_queue being reported
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* @fmt: printf format string
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* @args: printf args
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*
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* The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a
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* throtl_grp; otherwise, just "throtl".
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*
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* TODO: this should be made a function and name formatting should happen
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* after testing whether blktrace is enabled.
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*/
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#define throtl_log(sq, fmt, args...) do { \
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struct throtl_grp *__tg = sq_to_tg((sq)); \
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struct throtl_data *__td = sq_to_td((sq)); \
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\
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(void)__td; \
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if ((__tg)) { \
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char __pbuf[128]; \
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\
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blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \
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blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \
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} else { \
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blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \
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} \
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} while (0)
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static void tg_stats_init(struct tg_stats_cpu *tg_stats)
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{
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blkg_rwstat_init(&tg_stats->service_bytes);
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blkg_rwstat_init(&tg_stats->serviced);
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}
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/*
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* Worker for allocating per cpu stat for tgs. This is scheduled on the
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* system_wq once there are some groups on the alloc_list waiting for
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* allocation.
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*/
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static void tg_stats_alloc_fn(struct work_struct *work)
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{
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static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */
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struct delayed_work *dwork = to_delayed_work(work);
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bool empty = false;
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alloc_stats:
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if (!stats_cpu) {
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int cpu;
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stats_cpu = alloc_percpu(struct tg_stats_cpu);
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if (!stats_cpu) {
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/* allocation failed, try again after some time */
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schedule_delayed_work(dwork, msecs_to_jiffies(10));
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return;
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}
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for_each_possible_cpu(cpu)
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tg_stats_init(per_cpu_ptr(stats_cpu, cpu));
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}
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spin_lock_irq(&tg_stats_alloc_lock);
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if (!list_empty(&tg_stats_alloc_list)) {
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struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
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struct throtl_grp,
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stats_alloc_node);
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swap(tg->stats_cpu, stats_cpu);
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list_del_init(&tg->stats_alloc_node);
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}
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empty = list_empty(&tg_stats_alloc_list);
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spin_unlock_irq(&tg_stats_alloc_lock);
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if (!empty)
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goto alloc_stats;
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}
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static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg)
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{
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INIT_LIST_HEAD(&qn->node);
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bio_list_init(&qn->bios);
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qn->tg = tg;
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}
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/**
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* throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it
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* @bio: bio being added
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* @qn: qnode to add bio to
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* @queued: the service_queue->queued[] list @qn belongs to
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*
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* Add @bio to @qn and put @qn on @queued if it's not already on.
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* @qn->tg's reference count is bumped when @qn is activated. See the
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* comment on top of throtl_qnode definition for details.
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*/
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static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn,
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struct list_head *queued)
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{
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bio_list_add(&qn->bios, bio);
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if (list_empty(&qn->node)) {
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list_add_tail(&qn->node, queued);
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blkg_get(tg_to_blkg(qn->tg));
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}
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}
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/**
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* throtl_peek_queued - peek the first bio on a qnode list
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* @queued: the qnode list to peek
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*/
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static struct bio *throtl_peek_queued(struct list_head *queued)
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{
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struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node);
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struct bio *bio;
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if (list_empty(queued))
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return NULL;
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bio = bio_list_peek(&qn->bios);
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WARN_ON_ONCE(!bio);
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return bio;
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}
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/**
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* throtl_pop_queued - pop the first bio form a qnode list
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* @queued: the qnode list to pop a bio from
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* @tg_to_put: optional out argument for throtl_grp to put
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*
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* Pop the first bio from the qnode list @queued. After popping, the first
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* qnode is removed from @queued if empty or moved to the end of @queued so
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* that the popping order is round-robin.
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*
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* When the first qnode is removed, its associated throtl_grp should be put
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* too. If @tg_to_put is NULL, this function automatically puts it;
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* otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is
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* responsible for putting it.
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*/
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static struct bio *throtl_pop_queued(struct list_head *queued,
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struct throtl_grp **tg_to_put)
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{
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struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node);
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struct bio *bio;
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if (list_empty(queued))
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return NULL;
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bio = bio_list_pop(&qn->bios);
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WARN_ON_ONCE(!bio);
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if (bio_list_empty(&qn->bios)) {
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list_del_init(&qn->node);
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if (tg_to_put)
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*tg_to_put = qn->tg;
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else
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blkg_put(tg_to_blkg(qn->tg));
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} else {
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list_move_tail(&qn->node, queued);
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}
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return bio;
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}
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/* init a service_queue, assumes the caller zeroed it */
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static void throtl_service_queue_init(struct throtl_service_queue *sq,
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struct throtl_service_queue *parent_sq)
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{
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INIT_LIST_HEAD(&sq->queued[0]);
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INIT_LIST_HEAD(&sq->queued[1]);
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sq->pending_tree = RB_ROOT;
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sq->parent_sq = parent_sq;
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setup_timer(&sq->pending_timer, throtl_pending_timer_fn,
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(unsigned long)sq);
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}
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static void throtl_service_queue_exit(struct throtl_service_queue *sq)
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{
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del_timer_sync(&sq->pending_timer);
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}
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static void throtl_pd_init(struct blkcg_gq *blkg)
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{
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struct throtl_grp *tg = blkg_to_tg(blkg);
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struct throtl_data *td = blkg->q->td;
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struct throtl_service_queue *parent_sq;
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unsigned long flags;
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int rw;
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/*
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* If sane_hierarchy is enabled, we switch to properly hierarchical
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* behavior where limits on a given throtl_grp are applied to the
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* whole subtree rather than just the group itself. e.g. If 16M
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* read_bps limit is set on the root group, the whole system can't
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* exceed 16M for the device.
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*
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* If sane_hierarchy is not enabled, the broken flat hierarchy
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* behavior is retained where all throtl_grps are treated as if
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* they're all separate root groups right below throtl_data.
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* Limits of a group don't interact with limits of other groups
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* regardless of the position of the group in the hierarchy.
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*/
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parent_sq = &td->service_queue;
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if (cgroup_sane_behavior(blkg->blkcg->css.cgroup) && blkg->parent)
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parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
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throtl_service_queue_init(&tg->service_queue, parent_sq);
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for (rw = READ; rw <= WRITE; rw++) {
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throtl_qnode_init(&tg->qnode_on_self[rw], tg);
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throtl_qnode_init(&tg->qnode_on_parent[rw], tg);
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}
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RB_CLEAR_NODE(&tg->rb_node);
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tg->td = td;
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tg->bps[READ] = -1;
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tg->bps[WRITE] = -1;
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tg->iops[READ] = -1;
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tg->iops[WRITE] = -1;
|
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|
|
/*
|
|
* Ugh... We need to perform per-cpu allocation for tg->stats_cpu
|
|
* but percpu allocator can't be called from IO path. Queue tg on
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* tg_stats_alloc_list and allocate from work item.
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*/
|
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spin_lock_irqsave(&tg_stats_alloc_lock, flags);
|
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list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
|
|
schedule_delayed_work(&tg_stats_alloc_work, 0);
|
|
spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Set has_rules[] if @tg or any of its parents have limits configured.
|
|
* This doesn't require walking up to the top of the hierarchy as the
|
|
* parent's has_rules[] is guaranteed to be correct.
|
|
*/
|
|
static void tg_update_has_rules(struct throtl_grp *tg)
|
|
{
|
|
struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
|
|
int rw;
|
|
|
|
for (rw = READ; rw <= WRITE; rw++)
|
|
tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
|
|
(tg->bps[rw] != -1 || tg->iops[rw] != -1);
|
|
}
|
|
|
|
static void throtl_pd_online(struct blkcg_gq *blkg)
|
|
{
|
|
/*
|
|
* We don't want new groups to escape the limits of its ancestors.
|
|
* Update has_rules[] after a new group is brought online.
|
|
*/
|
|
tg_update_has_rules(blkg_to_tg(blkg));
|
|
}
|
|
|
|
static void throtl_pd_exit(struct blkcg_gq *blkg)
|
|
{
|
|
struct throtl_grp *tg = blkg_to_tg(blkg);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&tg_stats_alloc_lock, flags);
|
|
list_del_init(&tg->stats_alloc_node);
|
|
spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
|
|
|
|
free_percpu(tg->stats_cpu);
|
|
|
|
throtl_service_queue_exit(&tg->service_queue);
|
|
}
|
|
|
|
static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
|
|
{
|
|
struct throtl_grp *tg = blkg_to_tg(blkg);
|
|
int cpu;
|
|
|
|
if (tg->stats_cpu == NULL)
|
|
return;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
|
|
|
|
blkg_rwstat_reset(&sc->service_bytes);
|
|
blkg_rwstat_reset(&sc->serviced);
|
|
}
|
|
}
|
|
|
|
static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
|
|
struct blkcg *blkcg)
|
|
{
|
|
/*
|
|
* This is the common case when there are no blkcgs. Avoid lookup
|
|
* in this case
|
|
*/
|
|
if (blkcg == &blkcg_root)
|
|
return td_root_tg(td);
|
|
|
|
return blkg_to_tg(blkg_lookup(blkcg, td->queue));
|
|
}
|
|
|
|
static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
|
|
struct blkcg *blkcg)
|
|
{
|
|
struct request_queue *q = td->queue;
|
|
struct throtl_grp *tg = NULL;
|
|
|
|
/*
|
|
* This is the common case when there are no blkcgs. Avoid lookup
|
|
* in this case
|
|
*/
|
|
if (blkcg == &blkcg_root) {
|
|
tg = td_root_tg(td);
|
|
} else {
|
|
struct blkcg_gq *blkg;
|
|
|
|
blkg = blkg_lookup_create(blkcg, q);
|
|
|
|
/* if %NULL and @q is alive, fall back to root_tg */
|
|
if (!IS_ERR(blkg))
|
|
tg = blkg_to_tg(blkg);
|
|
else if (!blk_queue_dying(q))
|
|
tg = td_root_tg(td);
|
|
}
|
|
|
|
return tg;
|
|
}
|
|
|
|
static struct throtl_grp *
|
|
throtl_rb_first(struct throtl_service_queue *parent_sq)
|
|
{
|
|
/* Service tree is empty */
|
|
if (!parent_sq->nr_pending)
|
|
return NULL;
|
|
|
|
if (!parent_sq->first_pending)
|
|
parent_sq->first_pending = rb_first(&parent_sq->pending_tree);
|
|
|
|
if (parent_sq->first_pending)
|
|
return rb_entry_tg(parent_sq->first_pending);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
|
|
{
|
|
rb_erase(n, root);
|
|
RB_CLEAR_NODE(n);
|
|
}
|
|
|
|
static void throtl_rb_erase(struct rb_node *n,
|
|
struct throtl_service_queue *parent_sq)
|
|
{
|
|
if (parent_sq->first_pending == n)
|
|
parent_sq->first_pending = NULL;
|
|
rb_erase_init(n, &parent_sq->pending_tree);
|
|
--parent_sq->nr_pending;
|
|
}
|
|
|
|
static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)
|
|
{
|
|
struct throtl_grp *tg;
|
|
|
|
tg = throtl_rb_first(parent_sq);
|
|
if (!tg)
|
|
return;
|
|
|
|
parent_sq->first_pending_disptime = tg->disptime;
|
|
}
|
|
|
|
static void tg_service_queue_add(struct throtl_grp *tg)
|
|
{
|
|
struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;
|
|
struct rb_node **node = &parent_sq->pending_tree.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct throtl_grp *__tg;
|
|
unsigned long key = tg->disptime;
|
|
int left = 1;
|
|
|
|
while (*node != NULL) {
|
|
parent = *node;
|
|
__tg = rb_entry_tg(parent);
|
|
|
|
if (time_before(key, __tg->disptime))
|
|
node = &parent->rb_left;
|
|
else {
|
|
node = &parent->rb_right;
|
|
left = 0;
|
|
}
|
|
}
|
|
|
|
if (left)
|
|
parent_sq->first_pending = &tg->rb_node;
|
|
|
|
rb_link_node(&tg->rb_node, parent, node);
|
|
rb_insert_color(&tg->rb_node, &parent_sq->pending_tree);
|
|
}
|
|
|
|
static void __throtl_enqueue_tg(struct throtl_grp *tg)
|
|
{
|
|
tg_service_queue_add(tg);
|
|
tg->flags |= THROTL_TG_PENDING;
|
|
tg->service_queue.parent_sq->nr_pending++;
|
|
}
|
|
|
|
static void throtl_enqueue_tg(struct throtl_grp *tg)
|
|
{
|
|
if (!(tg->flags & THROTL_TG_PENDING))
|
|
__throtl_enqueue_tg(tg);
|
|
}
|
|
|
|
static void __throtl_dequeue_tg(struct throtl_grp *tg)
|
|
{
|
|
throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
|
|
tg->flags &= ~THROTL_TG_PENDING;
|
|
}
|
|
|
|
static void throtl_dequeue_tg(struct throtl_grp *tg)
|
|
{
|
|
if (tg->flags & THROTL_TG_PENDING)
|
|
__throtl_dequeue_tg(tg);
|
|
}
|
|
|
|
/* Call with queue lock held */
|
|
static void throtl_schedule_pending_timer(struct throtl_service_queue *sq,
|
|
unsigned long expires)
|
|
{
|
|
mod_timer(&sq->pending_timer, expires);
|
|
throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu",
|
|
expires - jiffies, jiffies);
|
|
}
|
|
|
|
/**
|
|
* throtl_schedule_next_dispatch - schedule the next dispatch cycle
|
|
* @sq: the service_queue to schedule dispatch for
|
|
* @force: force scheduling
|
|
*
|
|
* Arm @sq->pending_timer so that the next dispatch cycle starts on the
|
|
* dispatch time of the first pending child. Returns %true if either timer
|
|
* is armed or there's no pending child left. %false if the current
|
|
* dispatch window is still open and the caller should continue
|
|
* dispatching.
|
|
*
|
|
* If @force is %true, the dispatch timer is always scheduled and this
|
|
* function is guaranteed to return %true. This is to be used when the
|
|
* caller can't dispatch itself and needs to invoke pending_timer
|
|
* unconditionally. Note that forced scheduling is likely to induce short
|
|
* delay before dispatch starts even if @sq->first_pending_disptime is not
|
|
* in the future and thus shouldn't be used in hot paths.
|
|
*/
|
|
static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq,
|
|
bool force)
|
|
{
|
|
/* any pending children left? */
|
|
if (!sq->nr_pending)
|
|
return true;
|
|
|
|
update_min_dispatch_time(sq);
|
|
|
|
/* is the next dispatch time in the future? */
|
|
if (force || time_after(sq->first_pending_disptime, jiffies)) {
|
|
throtl_schedule_pending_timer(sq, sq->first_pending_disptime);
|
|
return true;
|
|
}
|
|
|
|
/* tell the caller to continue dispatching */
|
|
return false;
|
|
}
|
|
|
|
static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg,
|
|
bool rw, unsigned long start)
|
|
{
|
|
tg->bytes_disp[rw] = 0;
|
|
tg->io_disp[rw] = 0;
|
|
|
|
/*
|
|
* Previous slice has expired. We must have trimmed it after last
|
|
* bio dispatch. That means since start of last slice, we never used
|
|
* that bandwidth. Do try to make use of that bandwidth while giving
|
|
* credit.
|
|
*/
|
|
if (time_after_eq(start, tg->slice_start[rw]))
|
|
tg->slice_start[rw] = start;
|
|
|
|
tg->slice_end[rw] = jiffies + throtl_slice;
|
|
throtl_log(&tg->service_queue,
|
|
"[%c] new slice with credit start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', tg->slice_start[rw],
|
|
tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
|
|
{
|
|
tg->bytes_disp[rw] = 0;
|
|
tg->io_disp[rw] = 0;
|
|
tg->slice_start[rw] = jiffies;
|
|
tg->slice_end[rw] = jiffies + throtl_slice;
|
|
throtl_log(&tg->service_queue,
|
|
"[%c] new slice start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', tg->slice_start[rw],
|
|
tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,
|
|
unsigned long jiffy_end)
|
|
{
|
|
tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
|
|
}
|
|
|
|
static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,
|
|
unsigned long jiffy_end)
|
|
{
|
|
tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
|
|
throtl_log(&tg->service_queue,
|
|
"[%c] extend slice start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', tg->slice_start[rw],
|
|
tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
/* Determine if previously allocated or extended slice is complete or not */
|
|
static bool throtl_slice_used(struct throtl_grp *tg, bool rw)
|
|
{
|
|
if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
|
|
return false;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Trim the used slices and adjust slice start accordingly */
|
|
static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
|
|
{
|
|
unsigned long nr_slices, time_elapsed, io_trim;
|
|
u64 bytes_trim, tmp;
|
|
|
|
BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
|
|
|
|
/*
|
|
* If bps are unlimited (-1), then time slice don't get
|
|
* renewed. Don't try to trim the slice if slice is used. A new
|
|
* slice will start when appropriate.
|
|
*/
|
|
if (throtl_slice_used(tg, rw))
|
|
return;
|
|
|
|
/*
|
|
* A bio has been dispatched. Also adjust slice_end. It might happen
|
|
* that initially cgroup limit was very low resulting in high
|
|
* slice_end, but later limit was bumped up and bio was dispached
|
|
* sooner, then we need to reduce slice_end. A high bogus slice_end
|
|
* is bad because it does not allow new slice to start.
|
|
*/
|
|
|
|
throtl_set_slice_end(tg, rw, jiffies + throtl_slice);
|
|
|
|
time_elapsed = jiffies - tg->slice_start[rw];
|
|
|
|
nr_slices = time_elapsed / throtl_slice;
|
|
|
|
if (!nr_slices)
|
|
return;
|
|
tmp = tg->bps[rw] * throtl_slice * nr_slices;
|
|
do_div(tmp, HZ);
|
|
bytes_trim = tmp;
|
|
|
|
io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
|
|
|
|
if (!bytes_trim && !io_trim)
|
|
return;
|
|
|
|
if (tg->bytes_disp[rw] >= bytes_trim)
|
|
tg->bytes_disp[rw] -= bytes_trim;
|
|
else
|
|
tg->bytes_disp[rw] = 0;
|
|
|
|
if (tg->io_disp[rw] >= io_trim)
|
|
tg->io_disp[rw] -= io_trim;
|
|
else
|
|
tg->io_disp[rw] = 0;
|
|
|
|
tg->slice_start[rw] += nr_slices * throtl_slice;
|
|
|
|
throtl_log(&tg->service_queue,
|
|
"[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
|
|
tg->slice_start[rw], tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
|
|
unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned int io_allowed;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
u64 tmp;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
/*
|
|
* jiffy_elapsed_rnd should not be a big value as minimum iops can be
|
|
* 1 then at max jiffy elapsed should be equivalent of 1 second as we
|
|
* will allow dispatch after 1 second and after that slice should
|
|
* have been trimmed.
|
|
*/
|
|
|
|
tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
|
|
if (tmp > UINT_MAX)
|
|
io_allowed = UINT_MAX;
|
|
else
|
|
io_allowed = tmp;
|
|
|
|
if (tg->io_disp[rw] + 1 <= io_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return true;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
|
|
|
|
if (jiffy_wait > jiffy_elapsed)
|
|
jiffy_wait = jiffy_wait - jiffy_elapsed;
|
|
else
|
|
jiffy_wait = 1;
|
|
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
|
|
unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
u64 bytes_allowed, extra_bytes, tmp;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
tmp = tg->bps[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
bytes_allowed = tmp;
|
|
|
|
if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return true;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed;
|
|
jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
|
|
|
|
if (!jiffy_wait)
|
|
jiffy_wait = 1;
|
|
|
|
/*
|
|
* This wait time is without taking into consideration the rounding
|
|
* up we did. Add that time also.
|
|
*/
|
|
jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Returns whether one can dispatch a bio or not. Also returns approx number
|
|
* of jiffies to wait before this bio is with-in IO rate and can be dispatched
|
|
*/
|
|
static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
|
|
unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
|
|
|
|
/*
|
|
* Currently whole state machine of group depends on first bio
|
|
* queued in the group bio list. So one should not be calling
|
|
* this function with a different bio if there are other bios
|
|
* queued.
|
|
*/
|
|
BUG_ON(tg->service_queue.nr_queued[rw] &&
|
|
bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
|
|
|
|
/* If tg->bps = -1, then BW is unlimited */
|
|
if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* If previous slice expired, start a new one otherwise renew/extend
|
|
* existing slice to make sure it is at least throtl_slice interval
|
|
* long since now.
|
|
*/
|
|
if (throtl_slice_used(tg, rw))
|
|
throtl_start_new_slice(tg, rw);
|
|
else {
|
|
if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
|
|
throtl_extend_slice(tg, rw, jiffies + throtl_slice);
|
|
}
|
|
|
|
if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&
|
|
tg_with_in_iops_limit(tg, bio, &iops_wait)) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
max_wait = max(bps_wait, iops_wait);
|
|
|
|
if (wait)
|
|
*wait = max_wait;
|
|
|
|
if (time_before(tg->slice_end[rw], jiffies + max_wait))
|
|
throtl_extend_slice(tg, rw, jiffies + max_wait);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
|
|
int rw)
|
|
{
|
|
struct throtl_grp *tg = blkg_to_tg(blkg);
|
|
struct tg_stats_cpu *stats_cpu;
|
|
unsigned long flags;
|
|
|
|
/* If per cpu stats are not allocated yet, don't do any accounting. */
|
|
if (tg->stats_cpu == NULL)
|
|
return;
|
|
|
|
/*
|
|
* Disabling interrupts to provide mutual exclusion between two
|
|
* writes on same cpu. It probably is not needed for 64bit. Not
|
|
* optimizing that case yet.
|
|
*/
|
|
local_irq_save(flags);
|
|
|
|
stats_cpu = this_cpu_ptr(tg->stats_cpu);
|
|
|
|
blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
|
|
blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
|
|
/* Charge the bio to the group */
|
|
tg->bytes_disp[rw] += bio->bi_iter.bi_size;
|
|
tg->io_disp[rw]++;
|
|
|
|
/*
|
|
* REQ_THROTTLED is used to prevent the same bio to be throttled
|
|
* more than once as a throttled bio will go through blk-throtl the
|
|
* second time when it eventually gets issued. Set it when a bio
|
|
* is being charged to a tg.
|
|
*
|
|
* Dispatch stats aren't recursive and each @bio should only be
|
|
* accounted by the @tg it was originally associated with. Let's
|
|
* update the stats when setting REQ_THROTTLED for the first time
|
|
* which is guaranteed to be for the @bio's original tg.
|
|
*/
|
|
if (!(bio->bi_rw & REQ_THROTTLED)) {
|
|
bio->bi_rw |= REQ_THROTTLED;
|
|
throtl_update_dispatch_stats(tg_to_blkg(tg),
|
|
bio->bi_iter.bi_size, bio->bi_rw);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* throtl_add_bio_tg - add a bio to the specified throtl_grp
|
|
* @bio: bio to add
|
|
* @qn: qnode to use
|
|
* @tg: the target throtl_grp
|
|
*
|
|
* Add @bio to @tg's service_queue using @qn. If @qn is not specified,
|
|
* tg->qnode_on_self[] is used.
|
|
*/
|
|
static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn,
|
|
struct throtl_grp *tg)
|
|
{
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
bool rw = bio_data_dir(bio);
|
|
|
|
if (!qn)
|
|
qn = &tg->qnode_on_self[rw];
|
|
|
|
/*
|
|
* If @tg doesn't currently have any bios queued in the same
|
|
* direction, queueing @bio can change when @tg should be
|
|
* dispatched. Mark that @tg was empty. This is automatically
|
|
* cleaered on the next tg_update_disptime().
|
|
*/
|
|
if (!sq->nr_queued[rw])
|
|
tg->flags |= THROTL_TG_WAS_EMPTY;
|
|
|
|
throtl_qnode_add_bio(bio, qn, &sq->queued[rw]);
|
|
|
|
sq->nr_queued[rw]++;
|
|
throtl_enqueue_tg(tg);
|
|
}
|
|
|
|
static void tg_update_disptime(struct throtl_grp *tg)
|
|
{
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
|
|
struct bio *bio;
|
|
|
|
if ((bio = throtl_peek_queued(&sq->queued[READ])))
|
|
tg_may_dispatch(tg, bio, &read_wait);
|
|
|
|
if ((bio = throtl_peek_queued(&sq->queued[WRITE])))
|
|
tg_may_dispatch(tg, bio, &write_wait);
|
|
|
|
min_wait = min(read_wait, write_wait);
|
|
disptime = jiffies + min_wait;
|
|
|
|
/* Update dispatch time */
|
|
throtl_dequeue_tg(tg);
|
|
tg->disptime = disptime;
|
|
throtl_enqueue_tg(tg);
|
|
|
|
/* see throtl_add_bio_tg() */
|
|
tg->flags &= ~THROTL_TG_WAS_EMPTY;
|
|
}
|
|
|
|
static void start_parent_slice_with_credit(struct throtl_grp *child_tg,
|
|
struct throtl_grp *parent_tg, bool rw)
|
|
{
|
|
if (throtl_slice_used(parent_tg, rw)) {
|
|
throtl_start_new_slice_with_credit(parent_tg, rw,
|
|
child_tg->slice_start[rw]);
|
|
}
|
|
|
|
}
|
|
|
|
static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)
|
|
{
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
struct throtl_service_queue *parent_sq = sq->parent_sq;
|
|
struct throtl_grp *parent_tg = sq_to_tg(parent_sq);
|
|
struct throtl_grp *tg_to_put = NULL;
|
|
struct bio *bio;
|
|
|
|
/*
|
|
* @bio is being transferred from @tg to @parent_sq. Popping a bio
|
|
* from @tg may put its reference and @parent_sq might end up
|
|
* getting released prematurely. Remember the tg to put and put it
|
|
* after @bio is transferred to @parent_sq.
|
|
*/
|
|
bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put);
|
|
sq->nr_queued[rw]--;
|
|
|
|
throtl_charge_bio(tg, bio);
|
|
|
|
/*
|
|
* If our parent is another tg, we just need to transfer @bio to
|
|
* the parent using throtl_add_bio_tg(). If our parent is
|
|
* @td->service_queue, @bio is ready to be issued. Put it on its
|
|
* bio_lists[] and decrease total number queued. The caller is
|
|
* responsible for issuing these bios.
|
|
*/
|
|
if (parent_tg) {
|
|
throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg);
|
|
start_parent_slice_with_credit(tg, parent_tg, rw);
|
|
} else {
|
|
throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw],
|
|
&parent_sq->queued[rw]);
|
|
BUG_ON(tg->td->nr_queued[rw] <= 0);
|
|
tg->td->nr_queued[rw]--;
|
|
}
|
|
|
|
throtl_trim_slice(tg, rw);
|
|
|
|
if (tg_to_put)
|
|
blkg_put(tg_to_blkg(tg_to_put));
|
|
}
|
|
|
|
static int throtl_dispatch_tg(struct throtl_grp *tg)
|
|
{
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
unsigned int nr_reads = 0, nr_writes = 0;
|
|
unsigned int max_nr_reads = throtl_grp_quantum*3/4;
|
|
unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
|
|
struct bio *bio;
|
|
|
|
/* Try to dispatch 75% READS and 25% WRITES */
|
|
|
|
while ((bio = throtl_peek_queued(&sq->queued[READ])) &&
|
|
tg_may_dispatch(tg, bio, NULL)) {
|
|
|
|
tg_dispatch_one_bio(tg, bio_data_dir(bio));
|
|
nr_reads++;
|
|
|
|
if (nr_reads >= max_nr_reads)
|
|
break;
|
|
}
|
|
|
|
while ((bio = throtl_peek_queued(&sq->queued[WRITE])) &&
|
|
tg_may_dispatch(tg, bio, NULL)) {
|
|
|
|
tg_dispatch_one_bio(tg, bio_data_dir(bio));
|
|
nr_writes++;
|
|
|
|
if (nr_writes >= max_nr_writes)
|
|
break;
|
|
}
|
|
|
|
return nr_reads + nr_writes;
|
|
}
|
|
|
|
static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
|
|
{
|
|
unsigned int nr_disp = 0;
|
|
|
|
while (1) {
|
|
struct throtl_grp *tg = throtl_rb_first(parent_sq);
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
|
|
if (!tg)
|
|
break;
|
|
|
|
if (time_before(jiffies, tg->disptime))
|
|
break;
|
|
|
|
throtl_dequeue_tg(tg);
|
|
|
|
nr_disp += throtl_dispatch_tg(tg);
|
|
|
|
if (sq->nr_queued[0] || sq->nr_queued[1])
|
|
tg_update_disptime(tg);
|
|
|
|
if (nr_disp >= throtl_quantum)
|
|
break;
|
|
}
|
|
|
|
return nr_disp;
|
|
}
|
|
|
|
/**
|
|
* throtl_pending_timer_fn - timer function for service_queue->pending_timer
|
|
* @arg: the throtl_service_queue being serviced
|
|
*
|
|
* This timer is armed when a child throtl_grp with active bio's become
|
|
* pending and queued on the service_queue's pending_tree and expires when
|
|
* the first child throtl_grp should be dispatched. This function
|
|
* dispatches bio's from the children throtl_grps to the parent
|
|
* service_queue.
|
|
*
|
|
* If the parent's parent is another throtl_grp, dispatching is propagated
|
|
* by either arming its pending_timer or repeating dispatch directly. If
|
|
* the top-level service_tree is reached, throtl_data->dispatch_work is
|
|
* kicked so that the ready bio's are issued.
|
|
*/
|
|
static void throtl_pending_timer_fn(unsigned long arg)
|
|
{
|
|
struct throtl_service_queue *sq = (void *)arg;
|
|
struct throtl_grp *tg = sq_to_tg(sq);
|
|
struct throtl_data *td = sq_to_td(sq);
|
|
struct request_queue *q = td->queue;
|
|
struct throtl_service_queue *parent_sq;
|
|
bool dispatched;
|
|
int ret;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
again:
|
|
parent_sq = sq->parent_sq;
|
|
dispatched = false;
|
|
|
|
while (true) {
|
|
throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",
|
|
sq->nr_queued[READ] + sq->nr_queued[WRITE],
|
|
sq->nr_queued[READ], sq->nr_queued[WRITE]);
|
|
|
|
ret = throtl_select_dispatch(sq);
|
|
if (ret) {
|
|
throtl_log(sq, "bios disp=%u", ret);
|
|
dispatched = true;
|
|
}
|
|
|
|
if (throtl_schedule_next_dispatch(sq, false))
|
|
break;
|
|
|
|
/* this dispatch windows is still open, relax and repeat */
|
|
spin_unlock_irq(q->queue_lock);
|
|
cpu_relax();
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
|
|
if (!dispatched)
|
|
goto out_unlock;
|
|
|
|
if (parent_sq) {
|
|
/* @parent_sq is another throl_grp, propagate dispatch */
|
|
if (tg->flags & THROTL_TG_WAS_EMPTY) {
|
|
tg_update_disptime(tg);
|
|
if (!throtl_schedule_next_dispatch(parent_sq, false)) {
|
|
/* window is already open, repeat dispatching */
|
|
sq = parent_sq;
|
|
tg = sq_to_tg(sq);
|
|
goto again;
|
|
}
|
|
}
|
|
} else {
|
|
/* reached the top-level, queue issueing */
|
|
queue_work(kthrotld_workqueue, &td->dispatch_work);
|
|
}
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/**
|
|
* blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work
|
|
* @work: work item being executed
|
|
*
|
|
* This function is queued for execution when bio's reach the bio_lists[]
|
|
* of throtl_data->service_queue. Those bio's are ready and issued by this
|
|
* function.
|
|
*/
|
|
static void blk_throtl_dispatch_work_fn(struct work_struct *work)
|
|
{
|
|
struct throtl_data *td = container_of(work, struct throtl_data,
|
|
dispatch_work);
|
|
struct throtl_service_queue *td_sq = &td->service_queue;
|
|
struct request_queue *q = td->queue;
|
|
struct bio_list bio_list_on_stack;
|
|
struct bio *bio;
|
|
struct blk_plug plug;
|
|
int rw;
|
|
|
|
bio_list_init(&bio_list_on_stack);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
for (rw = READ; rw <= WRITE; rw++)
|
|
while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL)))
|
|
bio_list_add(&bio_list_on_stack, bio);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
if (!bio_list_empty(&bio_list_on_stack)) {
|
|
blk_start_plug(&plug);
|
|
while((bio = bio_list_pop(&bio_list_on_stack)))
|
|
generic_make_request(bio);
|
|
blk_finish_plug(&plug);
|
|
}
|
|
}
|
|
|
|
static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
|
|
struct blkg_policy_data *pd, int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
struct blkg_rwstat rwstat = { }, tmp;
|
|
int i, cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
|
|
|
|
tmp = blkg_rwstat_read((void *)sc + off);
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
rwstat.cnt[i] += tmp.cnt[i];
|
|
}
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
static int tg_print_cpu_rwstat(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_cpu_rwstat,
|
|
&blkcg_policy_throtl, seq_cft(sf)->private, true);
|
|
return 0;
|
|
}
|
|
|
|
static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
u64 v = *(u64 *)((void *)tg + off);
|
|
|
|
if (v == -1)
|
|
return 0;
|
|
return __blkg_prfill_u64(sf, pd, v);
|
|
}
|
|
|
|
static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
unsigned int v = *(unsigned int *)((void *)tg + off);
|
|
|
|
if (v == -1)
|
|
return 0;
|
|
return __blkg_prfill_u64(sf, pd, v);
|
|
}
|
|
|
|
static int tg_print_conf_u64(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64,
|
|
&blkcg_policy_throtl, seq_cft(sf)->private, false);
|
|
return 0;
|
|
}
|
|
|
|
static int tg_print_conf_uint(struct seq_file *sf, void *v)
|
|
{
|
|
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint,
|
|
&blkcg_policy_throtl, seq_cft(sf)->private, false);
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t tg_set_conf(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off, bool is_u64)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(of_css(of));
|
|
struct blkg_conf_ctx ctx;
|
|
struct throtl_grp *tg;
|
|
struct throtl_service_queue *sq;
|
|
struct blkcg_gq *blkg;
|
|
struct cgroup_subsys_state *pos_css;
|
|
int ret;
|
|
|
|
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
|
|
if (ret)
|
|
return ret;
|
|
|
|
tg = blkg_to_tg(ctx.blkg);
|
|
sq = &tg->service_queue;
|
|
|
|
if (!ctx.v)
|
|
ctx.v = -1;
|
|
|
|
if (is_u64)
|
|
*(u64 *)((void *)tg + of_cft(of)->private) = ctx.v;
|
|
else
|
|
*(unsigned int *)((void *)tg + of_cft(of)->private) = ctx.v;
|
|
|
|
throtl_log(&tg->service_queue,
|
|
"limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
|
|
tg->bps[READ], tg->bps[WRITE],
|
|
tg->iops[READ], tg->iops[WRITE]);
|
|
|
|
/*
|
|
* Update has_rules[] flags for the updated tg's subtree. A tg is
|
|
* considered to have rules if either the tg itself or any of its
|
|
* ancestors has rules. This identifies groups without any
|
|
* restrictions in the whole hierarchy and allows them to bypass
|
|
* blk-throttle.
|
|
*/
|
|
blkg_for_each_descendant_pre(blkg, pos_css, ctx.blkg)
|
|
tg_update_has_rules(blkg_to_tg(blkg));
|
|
|
|
/*
|
|
* We're already holding queue_lock and know @tg is valid. Let's
|
|
* apply the new config directly.
|
|
*
|
|
* Restart the slices for both READ and WRITES. It might happen
|
|
* that a group's limit are dropped suddenly and we don't want to
|
|
* account recently dispatched IO with new low rate.
|
|
*/
|
|
throtl_start_new_slice(tg, 0);
|
|
throtl_start_new_slice(tg, 1);
|
|
|
|
if (tg->flags & THROTL_TG_PENDING) {
|
|
tg_update_disptime(tg);
|
|
throtl_schedule_next_dispatch(sq->parent_sq, true);
|
|
}
|
|
|
|
blkg_conf_finish(&ctx);
|
|
return nbytes;
|
|
}
|
|
|
|
static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return tg_set_conf(of, buf, nbytes, off, true);
|
|
}
|
|
|
|
static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return tg_set_conf(of, buf, nbytes, off, false);
|
|
}
|
|
|
|
static struct cftype throtl_files[] = {
|
|
{
|
|
.name = "throttle.read_bps_device",
|
|
.private = offsetof(struct throtl_grp, bps[READ]),
|
|
.seq_show = tg_print_conf_u64,
|
|
.write = tg_set_conf_u64,
|
|
},
|
|
{
|
|
.name = "throttle.write_bps_device",
|
|
.private = offsetof(struct throtl_grp, bps[WRITE]),
|
|
.seq_show = tg_print_conf_u64,
|
|
.write = tg_set_conf_u64,
|
|
},
|
|
{
|
|
.name = "throttle.read_iops_device",
|
|
.private = offsetof(struct throtl_grp, iops[READ]),
|
|
.seq_show = tg_print_conf_uint,
|
|
.write = tg_set_conf_uint,
|
|
},
|
|
{
|
|
.name = "throttle.write_iops_device",
|
|
.private = offsetof(struct throtl_grp, iops[WRITE]),
|
|
.seq_show = tg_print_conf_uint,
|
|
.write = tg_set_conf_uint,
|
|
},
|
|
{
|
|
.name = "throttle.io_service_bytes",
|
|
.private = offsetof(struct tg_stats_cpu, service_bytes),
|
|
.seq_show = tg_print_cpu_rwstat,
|
|
},
|
|
{
|
|
.name = "throttle.io_serviced",
|
|
.private = offsetof(struct tg_stats_cpu, serviced),
|
|
.seq_show = tg_print_cpu_rwstat,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
static void throtl_shutdown_wq(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
|
|
cancel_work_sync(&td->dispatch_work);
|
|
}
|
|
|
|
static struct blkcg_policy blkcg_policy_throtl = {
|
|
.pd_size = sizeof(struct throtl_grp),
|
|
.cftypes = throtl_files,
|
|
|
|
.pd_init_fn = throtl_pd_init,
|
|
.pd_online_fn = throtl_pd_online,
|
|
.pd_exit_fn = throtl_pd_exit,
|
|
.pd_reset_stats_fn = throtl_pd_reset_stats,
|
|
};
|
|
|
|
bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_qnode *qn = NULL;
|
|
struct throtl_grp *tg;
|
|
struct throtl_service_queue *sq;
|
|
bool rw = bio_data_dir(bio);
|
|
struct blkcg *blkcg;
|
|
bool throttled = false;
|
|
|
|
/* see throtl_charge_bio() */
|
|
if (bio->bi_rw & REQ_THROTTLED)
|
|
goto out;
|
|
|
|
/*
|
|
* A throtl_grp pointer retrieved under rcu can be used to access
|
|
* basic fields like stats and io rates. If a group has no rules,
|
|
* just update the dispatch stats in lockless manner and return.
|
|
*/
|
|
rcu_read_lock();
|
|
blkcg = bio_blkcg(bio);
|
|
tg = throtl_lookup_tg(td, blkcg);
|
|
if (tg) {
|
|
if (!tg->has_rules[rw]) {
|
|
throtl_update_dispatch_stats(tg_to_blkg(tg),
|
|
bio->bi_iter.bi_size, bio->bi_rw);
|
|
goto out_unlock_rcu;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Either group has not been allocated yet or it is not an unlimited
|
|
* IO group
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
tg = throtl_lookup_create_tg(td, blkcg);
|
|
if (unlikely(!tg))
|
|
goto out_unlock;
|
|
|
|
sq = &tg->service_queue;
|
|
|
|
while (true) {
|
|
/* throtl is FIFO - if bios are already queued, should queue */
|
|
if (sq->nr_queued[rw])
|
|
break;
|
|
|
|
/* if above limits, break to queue */
|
|
if (!tg_may_dispatch(tg, bio, NULL))
|
|
break;
|
|
|
|
/* within limits, let's charge and dispatch directly */
|
|
throtl_charge_bio(tg, bio);
|
|
|
|
/*
|
|
* We need to trim slice even when bios are not being queued
|
|
* otherwise it might happen that a bio is not queued for
|
|
* a long time and slice keeps on extending and trim is not
|
|
* called for a long time. Now if limits are reduced suddenly
|
|
* we take into account all the IO dispatched so far at new
|
|
* low rate and * newly queued IO gets a really long dispatch
|
|
* time.
|
|
*
|
|
* So keep on trimming slice even if bio is not queued.
|
|
*/
|
|
throtl_trim_slice(tg, rw);
|
|
|
|
/*
|
|
* @bio passed through this layer without being throttled.
|
|
* Climb up the ladder. If we''re already at the top, it
|
|
* can be executed directly.
|
|
*/
|
|
qn = &tg->qnode_on_parent[rw];
|
|
sq = sq->parent_sq;
|
|
tg = sq_to_tg(sq);
|
|
if (!tg)
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* out-of-limit, queue to @tg */
|
|
throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d",
|
|
rw == READ ? 'R' : 'W',
|
|
tg->bytes_disp[rw], bio->bi_iter.bi_size, tg->bps[rw],
|
|
tg->io_disp[rw], tg->iops[rw],
|
|
sq->nr_queued[READ], sq->nr_queued[WRITE]);
|
|
|
|
bio_associate_current(bio);
|
|
tg->td->nr_queued[rw]++;
|
|
throtl_add_bio_tg(bio, qn, tg);
|
|
throttled = true;
|
|
|
|
/*
|
|
* Update @tg's dispatch time and force schedule dispatch if @tg
|
|
* was empty before @bio. The forced scheduling isn't likely to
|
|
* cause undue delay as @bio is likely to be dispatched directly if
|
|
* its @tg's disptime is not in the future.
|
|
*/
|
|
if (tg->flags & THROTL_TG_WAS_EMPTY) {
|
|
tg_update_disptime(tg);
|
|
throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true);
|
|
}
|
|
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
out_unlock_rcu:
|
|
rcu_read_unlock();
|
|
out:
|
|
/*
|
|
* As multiple blk-throtls may stack in the same issue path, we
|
|
* don't want bios to leave with the flag set. Clear the flag if
|
|
* being issued.
|
|
*/
|
|
if (!throttled)
|
|
bio->bi_rw &= ~REQ_THROTTLED;
|
|
return throttled;
|
|
}
|
|
|
|
/*
|
|
* Dispatch all bios from all children tg's queued on @parent_sq. On
|
|
* return, @parent_sq is guaranteed to not have any active children tg's
|
|
* and all bios from previously active tg's are on @parent_sq->bio_lists[].
|
|
*/
|
|
static void tg_drain_bios(struct throtl_service_queue *parent_sq)
|
|
{
|
|
struct throtl_grp *tg;
|
|
|
|
while ((tg = throtl_rb_first(parent_sq))) {
|
|
struct throtl_service_queue *sq = &tg->service_queue;
|
|
struct bio *bio;
|
|
|
|
throtl_dequeue_tg(tg);
|
|
|
|
while ((bio = throtl_peek_queued(&sq->queued[READ])))
|
|
tg_dispatch_one_bio(tg, bio_data_dir(bio));
|
|
while ((bio = throtl_peek_queued(&sq->queued[WRITE])))
|
|
tg_dispatch_one_bio(tg, bio_data_dir(bio));
|
|
}
|
|
}
|
|
|
|
/**
|
|
* blk_throtl_drain - drain throttled bios
|
|
* @q: request_queue to drain throttled bios for
|
|
*
|
|
* Dispatch all currently throttled bios on @q through ->make_request_fn().
|
|
*/
|
|
void blk_throtl_drain(struct request_queue *q)
|
|
__releases(q->queue_lock) __acquires(q->queue_lock)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct blkcg_gq *blkg;
|
|
struct cgroup_subsys_state *pos_css;
|
|
struct bio *bio;
|
|
int rw;
|
|
|
|
queue_lockdep_assert_held(q);
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* Drain each tg while doing post-order walk on the blkg tree, so
|
|
* that all bios are propagated to td->service_queue. It'd be
|
|
* better to walk service_queue tree directly but blkg walk is
|
|
* easier.
|
|
*/
|
|
blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg)
|
|
tg_drain_bios(&blkg_to_tg(blkg)->service_queue);
|
|
|
|
/* finally, transfer bios from top-level tg's into the td */
|
|
tg_drain_bios(&td->service_queue);
|
|
|
|
rcu_read_unlock();
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/* all bios now should be in td->service_queue, issue them */
|
|
for (rw = READ; rw <= WRITE; rw++)
|
|
while ((bio = throtl_pop_queued(&td->service_queue.queued[rw],
|
|
NULL)))
|
|
generic_make_request(bio);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
|
|
int blk_throtl_init(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td;
|
|
int ret;
|
|
|
|
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
|
|
if (!td)
|
|
return -ENOMEM;
|
|
|
|
INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
|
|
throtl_service_queue_init(&td->service_queue, NULL);
|
|
|
|
q->td = td;
|
|
td->queue = q;
|
|
|
|
/* activate policy */
|
|
ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
|
|
if (ret)
|
|
kfree(td);
|
|
return ret;
|
|
}
|
|
|
|
void blk_throtl_exit(struct request_queue *q)
|
|
{
|
|
BUG_ON(!q->td);
|
|
throtl_shutdown_wq(q);
|
|
blkcg_deactivate_policy(q, &blkcg_policy_throtl);
|
|
kfree(q->td);
|
|
}
|
|
|
|
static int __init throtl_init(void)
|
|
{
|
|
kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
|
|
if (!kthrotld_workqueue)
|
|
panic("Failed to create kthrotld\n");
|
|
|
|
return blkcg_policy_register(&blkcg_policy_throtl);
|
|
}
|
|
|
|
module_init(throtl_init);
|