linux/arch/ia64/mm
Gary Hade c04fc586c1 mm: show node to memory section relationship with symlinks in sysfs
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>
2009-01-06 15:59:00 -08:00
..
contig.c [IA64] Put the space for cpu0 per-cpu area into .data section 2008-09-29 16:39:19 -07:00
discontig.c [IA64] fix the difference between node_mem_map and node_start_pfn 2008-11-04 11:31:12 -08:00
extable.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
fault.c [IA64] kprobes arch consolidation build fix 2008-03-06 09:49:01 -08:00
hugetlbpage.c GRU Driver: hardware data structures 2008-07-30 09:41:47 -07:00
init.c mm: show node to memory section relationship with symlinks in sysfs 2009-01-06 15:59:00 -08:00
ioremap.c [IA64] make ioremap avoid unsupported attributes 2007-03-30 09:37:41 -07:00
Makefile [PATCH] ia64: ioremap: check EFI for valid memory attributes 2006-03-26 08:56:54 -08:00
numa.c [IA64] Minimize per_cpu reservations. 2008-04-08 13:51:35 -07:00
tlb.c [IA64] Fix annoying IA64_TR_ALLOC_MAX message. 2008-10-17 13:47:53 -07:00