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author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2009-04-02 16:57:36 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-02 19:04:55 -0700 |
commit | 81d39c20f5ee2437d71709beb82597e2a38efbbc (patch) | |
tree | 56297eb00cfa2bc251b2c5e0e0330becafd39e33 /Documentation/preempt-locking.txt | |
parent | 14067bb3e24b96d92e22d19c18c0119edf5575e5 (diff) |
memcg: fix shrinking memory to return -EBUSY by fixing retry algorithm
As pointed out, shrinking memcg's limit should return -EBUSY after
reasonable retries. This patch tries to fix the current behavior of
shrink_usage.
Before looking into "shrink should return -EBUSY" problem, we should fix
hierarchical reclaim code. It compares current usage and current limit,
but it only makes sense when the kernel reclaims memory because hit
limits. This is also a problem.
What this patch does are.
1. add new argument "shrink" to hierarchical reclaim. If "shrink==true",
hierarchical reclaim returns immediately and the caller checks the kernel
should shrink more or not.
(At shrinking memory, usage is always smaller than limit. So check for
usage < limit is useless.)
2. For adjusting to above change, 2 changes in "shrink"'s retry path.
2-a. retry_count depends on # of children because the kernel visits
the children under hierarchy one by one.
2-b. rather than checking return value of hierarchical_reclaim's progress,
compares usage-before-shrink and usage-after-shrink.
If usage-before-shrink <= usage-after-shrink, retry_count is
decremented.
Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/preempt-locking.txt')
0 files changed, 0 insertions, 0 deletions