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Date: Mon, 18 Sep 2017 09:34:34 -0700 From: Johannes Weiner <hannes@...xchg.org> To: Taras Kondratiuk <takondra@...co.com> Cc: Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org, xe-linux-external@...co.com, Ruslan Ruslichenko <rruslich@...co.com>, linux-kernel@...r.kernel.org Subject: Re: Detecting page cache trashing state Hi Taras, On Fri, Sep 15, 2017 at 10:28:30AM -0700, Taras Kondratiuk wrote: > Quoting Michal Hocko (2017-09-15 07:36:19) > > On Thu 14-09-17 17:16:27, Taras Kondratiuk wrote: > > > Has somebody faced similar issue? How are you solving it? > > > > Yes this is a pain point for a _long_ time. And we still do not have a > > good answer upstream. Johannes has been playing in this area [1]. > > The main problem is that our OOM detection logic is based on the ability > > to reclaim memory to allocate new memory. And that is pretty much true > > for the pagecache when you are trashing. So we do not know that > > basically whole time is spent refaulting the memory back and forth. > > We do have some refault stats for the page cache but that is not > > integrated to the oom detection logic because this is really a > > non-trivial problem to solve without triggering early oom killer > > invocations. > > > > [1] http://lkml.kernel.org/r/20170727153010.23347-1-hannes@cmpxchg.org > > Thanks Michal. memdelay looks promising. We will check it. Great, I'm obviously interested in more users of it :) Please find attached the latest version of the patch series based on v4.13. It needs a bit more refactoring in the scheduler bits before resubmission, but it already contains a couple of fixes and improvements since the first version I sent out. Let me know if you need help rebasing to a different kernel version. View attachment "0001-sched-loadavg-consolidate-LOAD_INT-LOAD_FRAC-macros.patch" of type "text/x-diff" (3932 bytes) View attachment "0002-mm-workingset-tell-cache-transitions-from-workingset.patch" of type "text/x-diff" (14639 bytes) View attachment "0003-mm-sched-memdelay-memory-health-interface-for-system.patch" of type "text/x-diff" (35404 bytes)
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