c04fc586c1
Show node to memory section relationship with symlinks in sysfs
Add /sys/devices/system/node/nodeX/memoryY symlinks for all
the memory sections located on nodeX. For example:
/sys/devices/system/node/node1/memory135 -> ../../memory/memory135
indicates that memory section 135 resides on node1.
Also revises documentation to cover this change as well as updating
Documentation/ABI/testing/sysfs-devices-memory to include descriptions
of memory hotremove files 'phys_device', 'phys_index', and 'state'
that were previously not described there.
In addition to it always being a good policy to provide users with
the maximum possible amount of physical location information for
resources that can be hot-added and/or hot-removed, the following
are some (but likely not all) of the user benefits provided by
this change.
Immediate:
- Provides information needed to determine the specific node
on which a defective DIMM is located. This will reduce system
downtime when the node or defective DIMM is swapped out.
- Prevents unintended onlining of a memory section that was
previously offlined due to a defective DIMM. This could happen
during node hot-add when the user or node hot-add assist script
onlines _all_ offlined sections due to user or script inability
to identify the specific memory sections located on the hot-added
node. The consequences of reintroducing the defective memory
could be ugly.
- Provides information needed to vary the amount and distribution
of memory on specific nodes for testing or debugging purposes.
Future:
- Will provide information needed to identify the memory
sections that need to be offlined prior to physical removal
of a specific node.
Symlink creation during boot was tested on 2-node x86_64, 2-node
ppc64, and 2-node ia64 systems. Symlink creation during physical
memory hot-add tested on a 2-node x86_64 system.
Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
72 lines
1.9 KiB
C
72 lines
1.9 KiB
C
/*
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* include/linux/node.h - generic node definition
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*
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* This is mainly for topological representation. We define the
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* basic 'struct node' here, which can be embedded in per-arch
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* definitions of processors.
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*
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* Basic handling of the devices is done in drivers/base/node.c
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* and system devices are handled in drivers/base/sys.c.
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*
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* Nodes are exported via driverfs in the class/node/devices/
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* directory.
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*
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* Per-node interfaces can be implemented using a struct device_interface.
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* See the following for how to do this:
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* - drivers/base/intf.c
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* - Documentation/driver-model/interface.txt
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*/
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#ifndef _LINUX_NODE_H_
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#define _LINUX_NODE_H_
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#include <linux/sysdev.h>
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#include <linux/cpumask.h>
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struct node {
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struct sys_device sysdev;
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};
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struct memory_block;
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extern struct node node_devices[];
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extern int register_node(struct node *, int, struct node *);
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extern void unregister_node(struct node *node);
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#ifdef CONFIG_NUMA
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extern int register_one_node(int nid);
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extern void unregister_one_node(int nid);
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extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
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extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
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extern int register_mem_sect_under_node(struct memory_block *mem_blk,
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int nid);
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extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk);
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#else
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static inline int register_one_node(int nid)
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{
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return 0;
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}
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static inline int unregister_one_node(int nid)
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{
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return 0;
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}
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static inline int register_cpu_under_node(unsigned int cpu, unsigned int nid)
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{
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return 0;
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}
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static inline int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
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{
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return 0;
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}
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static inline int register_mem_sect_under_node(struct memory_block *mem_blk,
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int nid)
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{
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return 0;
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}
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static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
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{
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return 0;
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}
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#endif
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#define to_node(sys_device) container_of(sys_device, struct node, sysdev)
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#endif /* _LINUX_NODE_H_ */
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