From: Johannes Weiner <hannes@cmpxchg.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Luigi Semenzato <semenzato@google.com>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: PSI vs. CPU overhead for client computing
Date: Wed, 24 Apr 2019 12:36:49 -0400 [thread overview]
Message-ID: <20190424163649.GA14187@cmpxchg.org> (raw)
In-Reply-To: <CAJuCfpHGcDM8c19g_AxWa4FSx++YbTSE70CGW4TiKvrdAg3R+w@mail.gmail.com>
On Tue, Apr 23, 2019 at 03:04:16PM -0700, Suren Baghdasaryan wrote:
> On Tue, Apr 23, 2019 at 11:58 AM Luigi Semenzato <semenzato@google.com> wrote:
> > The chrome browser is a multi-process app and there is a lot of IPC. When
> > process A is blocked on memory allocation, it cannot respond to IPC
> > from process B, thus effectively both processes are blocked on
> > allocation, but we don't see that.
>
> I don't think PSI would account such an indirect stall when A is
> waiting for B and B is blocked on memory access. B's stall will be
> accounted for but I don't think A's blocked time will go into PSI
> calculations. The process inter-dependencies are probably out of scope
> for PSI.
Well, yes and no. We don't do explicit dependency tracking, but when A
is waiting on B it's also not considered productive, so it doesn't
factor into the equation. psi will see B blocked on memory and no
other productive processes, which means FULL state until B resumes.
prev parent reply other threads:[~2019-04-24 16:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 18:57 PSI vs. CPU overhead for client computing Luigi Semenzato
2019-04-23 22:04 ` Suren Baghdasaryan
2019-04-24 4:54 ` Luigi Semenzato
2019-04-24 14:49 ` Suren Baghdasaryan
2019-04-25 17:31 ` Luigi Semenzato
2019-04-24 16:36 ` Johannes Weiner [this message]
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