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Re: [PATCH v2] vmscan: do not force-scan file lru if its absolute size is small

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On Mon, Nov 23, 2015 at 01:39:33PM +0300, Vladimir Davydov wrote:
> We assume there is enough inactive page cache if the size of inactive
> file lru is greater than the size of active file lru, in which case we
> force-scan file lru ignoring anonymous pages. While this logic works
> fine when there are plenty of page cache pages, it fails if the size of
> file lru is small (several MB): in this case (lru_size >> prio) will be
> 0 for normal scan priorities, as a result, if inactive file lru happens
> to be larger than active file lru, anonymous pages of a cgroup will
> never get evicted unless the system experiences severe memory pressure,
> even if there are gigabytes of unused anonymous memory there, which is
> unfair in respect to other cgroups, whose workloads might be page cache
> oriented.
> 
> This patch attempts to fix this by elaborating the "enough inactive page
> cache" check: it makes it not only check that inactive lru size > active
> lru size, but also that we will scan something from the cgroup at the
> current scan priority. If these conditions do not hold, we proceed to
> SCAN_FRACT as usual.
> 
> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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[PATCH] vmscan: do not force-scan file lru if its absolute size is small Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-11-20 18:10 +0100
  Re: [PATCH] vmscan: do not force-scan file lru if its absolute size  is small Johannes Weiner <hannes@cmpxchg.org> - 2015-11-20 19:40 +0100
    Re: [PATCH] vmscan: do not force-scan file lru if its absolute size  is small Andrew Morton <akpm@linux-foundation.org> - 2015-11-20 22:50 +0100
      [PATCH v2] vmscan: do not force-scan file lru if its absolute size is small Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-11-23 11:40 +0100
        Re: [PATCH v2] vmscan: do not force-scan file lru if its absolute  size is small Michal Hocko <mhocko@kernel.org> - 2015-11-23 13:20 +0100
        Re: [PATCH v2] vmscan: do not force-scan file lru if its absolute  size is small Johannes Weiner <hannes@cmpxchg.org> - 2015-11-23 17:40 +0100

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