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authorBadari Pulavarty <pbadari@us.ibm.com>2008-07-24 00:28:19 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-24 13:47:21 -0400
commit5c755e9fd813810680abd56ec09a5f90143e815b (patch)
tree1686c0666f6bd630441957a53c546d90b0f61723 /Documentation
parent2f7f24eca31c4fc2fdb134b2ef743ccd67cfb9a9 (diff)
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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-devices-memory24
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
new file mode 100644
index 000000000000..7a16fe1e2270
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -0,0 +1,24 @@
1What: /sys/devices/system/memory
2Date: June 2008
3Contact: Badari Pulavarty <pbadari@us.ibm.com>
4Description:
5 The /sys/devices/system/memory contains a snapshot of the
6 internal state of the kernel memory blocks. Files could be
7 added or removed dynamically to represent hot-add/remove
8 operations.
9
10Users: hotplug memory add/remove tools
11 https://w3.opensource.ibm.com/projects/powerpc-utils/
12
13What: /sys/devices/system/memory/memoryX/removable
14Date: June 2008
15Contact: Badari Pulavarty <pbadari@us.ibm.com>
16Description:
17 The file /sys/devices/system/memory/memoryX/removable
18 indicates whether this memory block is removable or not.
19 This is useful for a user-level agent to determine
20 identify removable sections of the memory before attempting
21 potentially expensive hot-remove memory operation
22
23Users: hotplug memory remove tools
24 https://w3.opensource.ibm.com/projects/powerpc-utils/