From: Johannes Weiner <hannes@cmpxchg.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Daniel Drake <drake@endlessm.com>,
Vinayak Menon <vinmenon@codeaurora.org>,
Christopher Lameter <cl@linux.com>,
Mike Galbraith <efault@gmx.de>,
Shakeel Butt <shakeelb@google.com>,
Peter Enderborg <peter.enderborg@sony.com>,
linux-mm <linux-mm@kvack.org>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com
Subject: Re: [PATCH 2/9] mm: workingset: tell cache transitions from workingset thrashing
Date: Thu, 2 Aug 2018 08:28:52 -0400 [thread overview]
Message-ID: <20180802122852.GA17974@cmpxchg.org> (raw)
In-Reply-To: <CAJuCfpGZGPD+k+jHDowWyvZPnUXzQ9n98wBycDZLAWOn=vV6Ew@mail.gmail.com>
Hi Suren,
On Wed, Aug 01, 2018 at 02:56:27PM -0700, Suren Baghdasaryan wrote:
> On Wed, Aug 1, 2018 at 8:19 AM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> > /*
> > - * The unsigned subtraction here gives an accurate distance
> > - * across inactive_age overflows in most cases.
> > + * Calculate the refault distance
> > *
> > - * There is a special case: usually, shadow entries have a
> > - * short lifetime and are either refaulted or reclaimed along
> > - * with the inode before they get too old. But it is not
> > - * impossible for the inactive_age to lap a shadow entry in
> > - * the field, which can then can result in a false small
> > - * refault distance, leading to a false activation should this
> > - * old entry actually refault again. However, earlier kernels
> > - * used to deactivate unconditionally with *every* reclaim
> > - * invocation for the longest time, so the occasional
> > - * inappropriate activation leading to pressure on the active
> > - * list is not a problem.
> > + * The unsigned subtraction here gives an accurate distance
> > + * across inactive_age overflows in most cases. There is a
> > + * special case: usually, shadow entries have a short lifetime
> > + * and are either refaulted or reclaimed along with the inode
> > + * before they get too old. But it is not impossible for the
> > + * inactive_age to lap a shadow entry in the field, which can
> > + * then can result in a false small refault distance, leading
>
> "which can then can" - please remove one of the "can".
Good catch, will fix.
next prev parent reply other threads:[~2018-08-02 12:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-01 15:19 [PATCH 0/9] psi: pressure stall information for CPU, memory, and IO v3 Johannes Weiner
2018-08-01 15:19 ` [PATCH 1/9] mm: workingset: don't drop refault information prematurely Johannes Weiner
2018-08-01 15:19 ` [PATCH 2/9] mm: workingset: tell cache transitions from workingset thrashing Johannes Weiner
2018-08-01 21:56 ` Suren Baghdasaryan
2018-08-02 12:28 ` Johannes Weiner [this message]
2018-08-01 15:19 ` [PATCH 3/9] delayacct: track delays from thrashing cache pages Johannes Weiner
2018-08-01 15:19 ` [PATCH 4/9] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD Johannes Weiner
2018-08-01 15:19 ` [PATCH 5/9] sched: loadavg: make calc_load_n() public Johannes Weiner
2018-08-01 15:19 ` [PATCH 6/9] sched: sched.h: make rq locking and clock functions available in stats.h Johannes Weiner
2018-08-01 15:19 ` [PATCH 7/9] sched: introduce this_rq_lock_irq() Johannes Weiner
2018-08-01 15:19 ` [PATCH 8/9] psi: pressure stall information for CPU, memory, and IO Johannes Weiner
2018-08-03 16:56 ` Peter Zijlstra
2018-08-06 15:05 ` Johannes Weiner
2018-08-06 15:25 ` Peter Zijlstra
2018-08-06 15:40 ` Johannes Weiner
2018-08-06 15:19 ` Johannes Weiner
2018-08-06 16:03 ` Peter Zijlstra
2018-08-21 19:44 ` Johannes Weiner
2018-08-22 9:16 ` Peter Zijlstra
2018-08-03 17:07 ` Peter Zijlstra
2018-08-06 15:23 ` Johannes Weiner
2018-08-03 17:15 ` Peter Zijlstra
2018-08-03 17:21 ` Peter Zijlstra
2018-08-21 20:11 ` Johannes Weiner
2018-08-22 9:10 ` Peter Zijlstra
2018-08-22 17:28 ` Johannes Weiner
2018-08-01 15:19 ` [PATCH 9/9] psi: cgroup support Johannes Weiner
2018-08-07 11:50 ` [PATCH 0/9] psi: pressure stall information for CPU, memory, and IO v3 peter enderborg
2018-08-07 17:51 ` Johannes Weiner
-- strict thread matches above, loose matches on Subject: below --
2018-08-28 17:22 [PATCH 0/9] psi: pressure stall information for CPU, memory, and IO v4 Johannes Weiner
2018-08-28 17:22 ` [PATCH 2/9] mm: workingset: tell cache transitions from workingset thrashing Johannes Weiner
2018-08-01 15:12 Johannes Weiner
2018-08-01 15:13 ` [PATCH 2/9] mm: workingset: tell cache transitions from workingset thrashing Johannes Weiner
2018-08-02 6:57 ` peter enderborg
2018-08-02 12:38 ` Johannes Weiner
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