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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2008-07-25 01:47:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:37 -0700
commite8589cc189f96b87348ae83ea4db38eaac624135 (patch)
tree6693422dc81e6da78c4ad892b0d326fb7f946dda /mm/rmap.c
parent508b7be0a5b06b64203512ed9b34191cddc83f56 (diff)
downloadop-kernel-dev-e8589cc189f96b87348ae83ea4db38eaac624135.zip
op-kernel-dev-e8589cc189f96b87348ae83ea4db38eaac624135.tar.gz
memcg: better migration handling
This patch changes page migration under memory controller to use a different algorithm. (thanks to Christoph for new idea.) Before: - page_cgroup is migrated from an old page to a new page. After: - a new page is accounted , no reuse of page_cgroup. Pros: - We can avoid compliated lock depndencies and races in migration. Cons: - new param to mem_cgroup_charge_common(). - mem_cgroup_getref() is added for handling ref_cnt ping-pong. This version simplifies complicated lock dependency in page migraiton under memory resource controller. new refcnt sequence is following. a mapped page: prepage_migration() ..... +1 to NEW page try_to_unmap() ..... all refs to OLD page is gone. move_pages() ..... +1 to NEW page if page cache. remap... ..... all refs from *map* is added to NEW one. end_migration() ..... -1 to New page. page's mapcount + (page_is_cache) refs are added to NEW one. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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