From: Dave Jones <davej@codemonkey.org.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Linux Kernel <linux-kernel@vger.kernel.org>,
mingo@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: weird loadavg on idle machine post 5.7
Date: Fri, 3 Jul 2020 16:51:53 -0400 [thread overview]
Message-ID: <20200703205153.GA19901@codemonkey.org.uk> (raw)
In-Reply-To: <20200703104033.GK117543@hirez.programming.kicks-ass.net>
On Fri, Jul 03, 2020 at 12:40:33PM +0200, Peter Zijlstra wrote:
> So ARM/Power/etc.. can speculate the load such that the
> task_contributes_to_load() value is from before ->on_rq.
>
> The compiler might similar re-order things -- although I've not found it
> doing so with the few builds I looked at.
>
> So I think at the very least we should do something like this. But i've
> no idea how to reproduce this problem.
>
> Mel's patch placed it too far down, as the WF_ON_CPU path also relies on
> this, and by not resetting p->sched_contributes_to_load it would skew
> accounting even worse.
looked promising the first few hours, but as soon as it hit four hours
of uptime, loadavg spiked and is now pinned to at least 1.00
Dave
next prev parent reply other threads:[~2020-07-03 20:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 17:15 weird loadavg on idle machine post 5.7 Dave Jones
2020-07-02 19:46 ` Dave Jones
2020-07-02 21:15 ` Paul Gortmaker
2020-07-03 13:23 ` Paul Gortmaker
2020-07-02 21:36 ` Mel Gorman
2020-07-02 23:11 ` Michal Kubecek
2020-07-02 23:24 ` Dave Jones
2020-07-03 9:02 ` Peter Zijlstra
2020-07-03 10:40 ` Peter Zijlstra
2020-07-03 20:51 ` Dave Jones [this message]
2020-07-06 14:59 ` Peter Zijlstra
2020-07-06 21:20 ` Dave Jones
2020-07-07 7:48 ` Peter Zijlstra
2020-07-06 23:56 ` Valentin Schneider
2020-07-07 8:17 ` Peter Zijlstra
2020-07-07 10:20 ` Valentin Schneider
2020-07-07 10:29 ` Peter Zijlstra
2020-07-08 9:46 ` [tip: sched/urgent] sched: Fix loadavg accounting race tip-bot2 for Peter Zijlstra
2020-07-07 9:20 ` weird loadavg on idle machine post 5.7 Qais Yousef
2020-07-07 9:47 ` Peter Zijlstra
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