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From: Michal Hocko <mhocko@suse.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>,
	David Hildenbrand <david@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mike Rapoport <rppt@kernel.org>,
	Oscar Salvador <osalvador@suse.de>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	mark.rutland@arm.com, will@kernel.org,
	virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-arm-msm@vger.kernel.org,
	Trilok Soni <quic_tsoni@quicinc.com>,
	Sukadev Bhattiprolu <quic_sukadev@quicinc.com>,
	Srivatsa Vaddagiri <quic_svaddagi@quicinc.com>,
	Patrick Daly <quic_pdaly@quicinc.com>
Subject: Re: [PATCH] psi: reduce min window size to 50ms
Date: Fri, 24 Feb 2023 13:47:35 +0100	[thread overview]
Message-ID: <Y/ix53x8i/ViuBXf@dhcp22.suse.cz> (raw)
In-Reply-To: <CAJuCfpHrhO7_fMwNuu2hdQob=MPjZTW8eaJpNhEhPmDMqz2qTA@mail.gmail.com>

On Tue 14-02-23 11:34:30, Suren Baghdasaryan wrote:
[...]
> Your suggestion to have this limit configurable sounds like obvious
> solution. I would like to get some opinions from other maintainers.
> Johannes, WDYT? CC'ing Michal to chime in as well since this is mostly
> related to memory stalls.

I do not think that making this configurable helps much. Many users will
be bound to distribution config and also it would be hard to experiment
with a recompile cycle every time. This seems just too impractical.

Is there any reason why we shouldn't allow any timeout? Shorter
timeouts could be restricted to a priviledged context to avoid an easy
way to swamp system by too frequent polling.

Btw. it seems that there is is only a limit on a single trigger per fd
but no limits per user so it doesn't sound too hard to end up with too
much polling even with a larger timeouts. To me it seems like we need to
contain the polling thread to be bound by the cpu controller.
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2023-02-24 12:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-10 22:31 Sudarshan Rajagopalan
2023-02-10 22:31 ` Sudarshan Rajagopalan
2023-02-10 23:03 ` Suren Baghdasaryan
2023-02-11  0:44   ` Sudarshan Rajagopalan
2023-02-11  1:09     ` Suren Baghdasaryan
2023-02-11  1:46       ` Sudarshan Rajagopalan
2023-02-11  2:13         ` Suren Baghdasaryan
2023-02-14  2:12           ` Sudarshan Rajagopalan
2023-02-14 19:34             ` Suren Baghdasaryan
2023-02-24 12:47               ` Michal Hocko [this message]
2023-02-24 21:07                 ` Suren Baghdasaryan
2023-02-27 13:34                   ` Michal Hocko
2023-02-27 17:49                     ` Suren Baghdasaryan
2023-02-27 19:11                       ` Michal Hocko
2023-02-27 19:50                         ` Suren Baghdasaryan
2023-02-28 13:50                           ` Michal Hocko
2023-02-28 18:18                             ` Suren Baghdasaryan
2023-03-01  1:49                               ` Suren Baghdasaryan
2023-02-27 19:19                       ` Josh Hunt
2023-02-27 19:51                         ` Suren Baghdasaryan

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