linux-hardened/mm
David Rientjes 73d342b169 slub: add min_partial sysfs tunable
Now that a cache's min_partial has been moved to struct kmem_cache, it's
possible to easily tune it from userspace by adding a sysfs attribute.

It may not be desirable to keep a large number of partial slabs around
if a cache is used infrequently and memory, especially when constrained
by a cgroup, is scarce.  It's better to allow userspace to set the
minimum policy per cache instead of relying explicitly on
kmem_cache_shrink().

The memory savings from simply moving min_partial from struct
kmem_cache_node to struct kmem_cache is obviously not significant
(unless maybe you're from SGI or something), at the largest it's

	# allocated caches * (MAX_NUMNODES - 1) * sizeof(unsigned long)

The true savings occurs when userspace reduces the number of partial
slabs that would otherwise be wasted, especially on machines with a
large number of nodes (ia64 with CONFIG_NODES_SHIFT at 10 for default?).
As well as the kernel estimates ideal values for n->min_partial and
ensures it's within a sane range, userspace has no other input other
than writing to /sys/kernel/slab/cache/shrink.

There simply isn't any better heuristic to add when calculating the
partial values for a better estimate that works for all possible caches.
And since it's currently a static value, the user really has no way of
reclaiming that wasted space, which can be significant when constrained
by a cgroup (either cpusets or, later, memory controller slab limits)
without shrinking it entirely.

This also allows the user to specify that increased fragmentation and
more partial slabs are actually desired to avoid the cost of allocating
new slabs at runtime for specific caches.

There's also no reason why this should be a per-struct kmem_cache_node
value in the first place.  You could argue that a machine would have
such node size asymmetries that it should be specified on a per-node
basis, but we know nobody is doing that right now since it's a purely
static value at the moment and there's no convenient way to tune that
via slub's sysfs interface.

Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-02-23 12:05:46 +02:00
..
allocpercpu.c mm/allocpercpu.c: make 4 functions static 2008-07-26 12:00:12 -07:00
backing-dev.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-06 17:10:04 -08:00
bootmem.c bootmem: print request details before BUG_ON(them) 2009-01-06 15:59:10 -08:00
bounce.c bounce: don't rely on a zeroed bio_vec list 2008-12-29 08:29:52 +01:00
dmapool.c dmapool: enable debugging for CONFIG_SLUB_DEBUG_ON too 2008-04-28 08:58:20 -07:00
fadvise.c [CVE-2009-0029] System call wrapper special cases 2009-01-14 14:15:18 +01:00
failslab.c SLUB: failslab support 2008-12-29 11:27:46 +02:00
filemap.c [CVE-2009-0029] System call wrapper special cases 2009-01-14 14:15:18 +01:00
filemap_xip.c badpage: remove vma from page_remove_rmap 2009-01-06 15:59:07 -08:00
fremap.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
highmem.c x86, pat: avoid highmem cache attribute aliasing 2008-08-15 17:22:57 +02:00
hugetlb.c Do not account for hugetlbfs quota at mmap() time if mapping [SHM|MAP]_NORESERVE 2009-02-11 12:38:09 -08:00
internal.h mm: make get_user_pages() interruptible 2009-01-06 15:59:08 -08:00
Kconfig Remove obsolete CONFIG_RESOURCES_64BIT 2009-01-06 15:59:14 -08:00
maccess.c kgdb: fix optional arch functions and probe_kernel_* 2008-04-17 20:05:39 +02:00
madvise.c [CVE-2009-0029] System call wrappers part 14 2009-01-14 14:15:24 +01:00
Makefile shmem: unify regular and tiny shmem 2009-01-06 15:59:08 -08:00
memcontrol.c memcg: NULL pointer dereference at rmdir on some NUMA systems 2009-01-29 18:04:44 -08:00
memory.c do_wp_page: fix regression with execute in place 2009-02-05 12:56:48 -08:00
memory_hotplug.c mm: remove GFP_HIGHUSER_PAGECACHE 2009-01-06 15:59:01 -08:00
mempolicy.c [CVE-2009-0029] System call wrappers part 28 2009-01-14 14:15:30 +01:00
mempool.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
migrate.c migration: migrate_vmas should check "vma" 2009-02-11 14:25:34 -08:00
mincore.c [CVE-2009-0029] System call wrappers part 14 2009-01-14 14:15:24 +01:00
mlock.c mm: fix error case in mlock downgrade reversion 2009-02-08 13:53:28 -08:00
mm_init.c mm: mminit_loglevel cannot be __meminitdata anymore 2008-08-20 15:40:30 -07:00
mmap.c mm: rearrange exit_mmap() to unlock before arch_exit_mmap 2009-02-11 14:25:37 -08:00
mmu_notifier.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
mmzone.c mm: mark the correct zone as full when scanning zonelists 2008-09-13 14:41:52 -07:00
mprotect.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
mremap.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
msync.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
nommu.c uclinux: add process name to allocation error message 2009-01-27 16:42:03 +10:00
oom_kill.c memcg: avoid deadlock caused by race between oom and cpuset_attach 2009-01-08 08:31:09 -08:00
page-writeback.c writeback: fix break condition 2009-02-11 14:25:37 -08:00
page_alloc.c mm: introduce zone_reclaim struct 2009-01-08 08:31:07 -08:00
page_cgroup.c memcg: use __GFP_NOWARN in page cgroup allocation 2009-02-11 14:25:35 -08:00
page_io.c mm: try_to_free_swap replaces remove_exclusive_swap_page 2009-01-06 15:59:03 -08:00
page_isolation.c memory hotplug: fix page_zone() calculation in test_pages_isolated() 2008-11-06 15:41:19 -08:00
pagewalk.c pagemap: pass mm into pagewalkers 2008-06-12 18:05:41 -07:00
pdflush.c cpumask: convert mm/ 2009-01-01 10:12:29 +10:30
prio_tree.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
quicklist.c mm: size of quicklists shouldn't be proportional to the number of CPUs 2008-09-02 19:21:38 -07:00
readahead.c vmscan: split LRU lists into anon & file sets 2008-10-20 08:50:25 -07:00
rmap.c mm: fix mlocked page counter mismatch 2009-02-11 14:25:35 -08:00
shmem.c Stop playing silly games with the VM_ACCOUNT flag 2009-01-31 15:08:56 -08:00
shmem_acl.c [PATCH] sanitize ->permission() prototype 2008-07-26 20:53:14 -04:00
slab.c cpumask: convert mm/ 2009-01-01 10:12:29 +10:30
slob.c slob: do not pass the SLAB flags as GFP in kmem_cache_create() 2008-12-15 16:27:06 -08:00
slub.c slub: add min_partial sysfs tunable 2009-02-23 12:05:46 +02:00
sparse-vmemmap.c vmemmap: warn about page_structs with remote distance 2008-11-06 15:41:19 -08:00
sparse.c meminit section warnings 2008-11-30 10:03:35 -08:00
swap.c memcg: add zone_reclaim_stat 2009-01-08 08:31:08 -08:00
swap_state.c memcg: mem+swap controller core 2009-01-08 08:31:05 -08:00
swapfile.c memcg: fix refcnt handling at swapoff 2009-01-29 18:04:43 -08:00
thrash.c Bug in mm/thrash.c function grab_swap_token() 2007-05-11 08:29:32 -07:00
truncate.c mmap: handle mlocked pages during map, remap, unmap 2008-10-20 08:52:31 -07:00
util.c mm: Make generic weak get_user_pages_fast and EXPORT_GPL it 2008-08-12 17:52:53 +10:00
vmalloc.c revert "mm: vmalloc use mutex for purge" 2009-01-15 16:39:40 -08:00
vmscan.c memcg: fix calculation of active_ratio 2009-01-08 08:31:09 -08:00
vmstat.c cpumask: convert mm/ 2009-01-01 10:12:29 +10:30