Messages in this thread | | | Date | Wed, 7 May 2014 14:15:34 -0700 | From | Andrew Morton <> | Subject | Re: [patch v3 2/6] mm, compaction: return failed migration target pages back to freelist |
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On Tue, 6 May 2014 19:22:43 -0700 (PDT) David Rientjes <rientjes@google.com> wrote:
> Memory compaction works by having a "freeing scanner" scan from one end of a > zone which isolates pages as migration targets while another "migrating scanner" > scans from the other end of the same zone which isolates pages for migration. > > When page migration fails for an isolated page, the target page is returned to > the system rather than the freelist built by the freeing scanner. This may > require the freeing scanner to continue scanning memory after suitable migration > targets have already been returned to the system needlessly. > > This patch returns destination pages to the freeing scanner freelist when page > migration fails. This prevents unnecessary work done by the freeing scanner but > also encourages memory to be as compacted as possible at the end of the zone. > > Reported-by: Greg Thelen <gthelen@google.com>
What did Greg actually report? IOW, what if any observable problem is being fixed here?
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