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author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2012-12-11 16:03:16 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-11 17:22:28 -0800 |
commit | 511c2aba8f07fc45bdcba548cb63f7b8a450c6dc (patch) | |
tree | 6a1a853e60e0004f5895d78231ed1bea33fecaac /Documentation | |
parent | fcf07d22f089856631b52a75c35ba3c33b70a1b4 (diff) | |
download | linux-511c2aba8f07fc45bdcba548cb63f7b8a450c6dc.tar.bz2 |
mm, memory-hotplug: dynamic configure movable memory and portion memory
Add online_movable and online_kernel for logic memory hotplug. This is
the dynamic version of "movablecore" & "kernelcore".
We have the same reason to introduce it as to introduce "movablecore" &
"kernelcore". It has the same motive as "movablecore" & "kernelcore", but
it is dynamic/running-time:
o We can configure memory as kernelcore or movablecore after boot.
Userspace workload is increased, we need more hugepage, we can't use
"online_movable" to add memory and allow the system use more
THP(transparent-huge-page), vice-verse when kernel workload is increase.
Also help for virtualization to dynamic configure host/guest's memory,
to save/(reduce waste) memory.
Memory capacity on Demand
o When a new node is physically online after boot, we need to use
"online_movable" or "online_kernel" to configure/portion it as we
expected when we logic-online it.
This configuration also helps for physically-memory-migrate.
o all benefit as the same as existed "movablecore" & "kernelcore".
o Preparing for movable-node, which is very important for power-saving,
hardware partitioning and high-available-system(hardware fault
management).
(Note, we don't introduce movable-node here.)
Action behavior:
When a memoryblock/memorysection is onlined by "online_movable", the kernel
will not have directly reference to the page of the memoryblock,
thus we can remove that memory any time when needed.
When it is online by "online_kernel", the kernel can use it.
When it is online by "online", the zone type doesn't changed.
Current constraints:
Only the memoryblock which is adjacent to the ZONE_MOVABLE
can be online from ZONE_NORMAL to ZONE_MOVABLE.
[akpm@linux-foundation.org: use min_t, cleanups]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Greg KH <greg@kroah.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/memory-hotplug.txt | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index 6e6cbc78f329..c6f993d491b5 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -161,7 +161,8 @@ a recent addition and not present on older kernels. in the memory block. 'state' : read-write at read: contains online/offline state of memory. - at write: user can specify "online", "offline" command + at write: user can specify "online_kernel", + "online_movable", "online", "offline" command which will be performed on al sections in the block. 'phys_device' : read-only: designed to show the name of physical memory device. This is not well implemented now. @@ -255,6 +256,17 @@ For onlining, you have to write "online" to the section's state file as: % echo online > /sys/devices/system/memory/memoryXXX/state +This onlining will not change the ZONE type of the target memory section, +If the memory section is in ZONE_NORMAL, you can change it to ZONE_MOVABLE: + +% echo online_movable > /sys/devices/system/memory/memoryXXX/state +(NOTE: current limit: this memory section must be adjacent to ZONE_MOVABLE) + +And if the memory section is in ZONE_MOVABLE, you can change it to ZONE_NORMAL: + +% echo online_kernel > /sys/devices/system/memory/memoryXXX/state +(NOTE: current limit: this memory section must be adjacent to ZONE_NORMAL) + After this, section memoryXXX's state will be 'online' and the amount of available memory will be increased. |