From 511c2aba8f07fc45bdcba548cb63f7b8a450c6dc Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 11 Dec 2012 16:03:16 -0800 Subject: 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 Signed-off-by: Wen Congyang Cc: Yasuaki Ishimatsu Cc: Lai Jiangshan Cc: Jiang Liu Cc: KOSAKI Motohiro Cc: Minchan Kim Cc: Mel Gorman Cc: David Rientjes Cc: Yinghai Lu Cc: Rusty Russell Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/memory-hotplug.txt | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'Documentation/memory-hotplug.txt') 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. -- cgit v1.2.3-59-g8ed1b