]> err.no Git - linux-2.6/commit
memory-hotplug: add sysfs removable attribute for hotplug memory remove
authorBadari Pulavarty <pbadari@us.ibm.com>
Thu, 24 Jul 2008 04:28:19 +0000 (21:28 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 24 Jul 2008 17:47:21 +0000 (10:47 -0700)
commit5c755e9fd813810680abd56ec09a5f90143e815b
tree1686c0666f6bd630441957a53c546d90b0f61723
parent2f7f24eca31c4fc2fdb134b2ef743ccd67cfb9a9
memory-hotplug: add sysfs removable attribute for hotplug memory remove

Memory may be hot-removed on a per-memory-block basis, particularly on
POWER where the SPARSEMEM section size often matches the memory-block
size.  A user-level agent must be able to identify which sections of
memory are likely to be removable before attempting the potentially
expensive operation.  This patch adds a file called "removable" to the
memory directory in sysfs to help such an agent.  In this patch, a memory
block is considered removable if;

o It contains only MOVABLE pageblocks
o It contains only pageblocks with free pages regardless of pageblock type

On the other hand, a memory block starting with a PageReserved() page will
never be considered removable.  Without this patch, the user-agent is
forced to choose a memory block to remove randomly.

Sample output of the sysfs files:

./memory/memory0/removable: 0
./memory/memory1/removable: 0
./memory/memory2/removable: 0
./memory/memory3/removable: 0
./memory/memory4/removable: 0
./memory/memory5/removable: 0
./memory/memory6/removable: 0
./memory/memory7/removable: 1
./memory/memory8/removable: 0
./memory/memory9/removable: 0
./memory/memory10/removable: 0
./memory/memory11/removable: 0
./memory/memory12/removable: 0
./memory/memory13/removable: 0
./memory/memory14/removable: 0
./memory/memory15/removable: 0
./memory/memory16/removable: 0
./memory/memory17/removable: 1
./memory/memory18/removable: 1
./memory/memory19/removable: 1
./memory/memory20/removable: 1
./memory/memory21/removable: 1
./memory/memory22/removable: 1

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/ABI/testing/sysfs-devices-memory [new file with mode: 0644]
drivers/base/memory.c
include/linux/memory_hotplug.h
mm/memory_hotplug.c