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authorPaul Jackson <pj@sgi.com>2006-01-08 01:02:00 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:13:44 -0800
commit04c19fa6f16047abff2288ddbc1f0798ede5a849 (patch)
tree4c4f109d919042b300ac907a8fde64b822faa7aa /init
parent4225399a66b315d4d1fb1cb61b75dda201c832e3 (diff)
[PATCH] cpuset: migrate all tasks in cpuset at once
Given the mechanism in the previous patch to handle rebinding the per-vma mempolicies of all tasks in a cpuset that changes its memory placement, it is now easier to handle the page migration requirements of such tasks at the same time. The previous code didn't actually attempt to migrate the pages of the tasks in a cpuset whose memory placement changed until the next time each such task tried to allocate memory. This was undesirable, as users invoking memory page migration exected to happen when the placement changed, not some unspecified time later when the task needed more memory. It is now trivial to handle the page migration at the same time as the per-vma rebinding is done. The routine cpuset.c:update_nodemask(), which handles changing a cpusets memory placement ('mems') now checks for the special case of being asked to write a placement that is the same as before. It was harmless enough before to just recompute everything again, even though nothing had changed. But page migration is a heavy weight operation - moving pages about. So now it is worth avoiding that if asked to move a cpuset to its current location. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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