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From: Balbir Singh <bsingharora@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, mingo@kernel.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com, pbonzini@redhat.com, maz@kernel.org,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	riel@surriel.com, hannes@cmpxchg.org
Subject: Re: [PATCH 0/6] sched,delayacct: Some cleanups
Date: Thu, 6 May 2021 08:29:40 +1000	[thread overview]
Message-ID: <20210505222940.GA4236@balbir-desktop> (raw)
In-Reply-To: <20210505105940.190490250@infradead.org>

On Wed, May 05, 2021 at 12:59:40PM +0200, Peter Zijlstra wrote:
> Hi,
> 
> Due to:
> 
>   https://lkml.kernel.org/r/0000000000001d43ac05c0f5c6a0@google.com
> 
> and general principle, delayacct really shouldn't be using ktime (pvclock also
> really shouldn't be doing what it does, but that's another story). This lead me
> to looking at the SCHED_INFO, SCHEDSTATS, DELAYACCT (and PSI) accounting hell.
> 
> The rest of the patches are an attempt at simplifying all that a little. All
> that crud is enabled by default for distros which is leading to a death by a
> thousand cuts.
> 
> The last patch is an attempt at default disabling DELAYACCT, because I don't
> think anybody actually uses that much, but what do I know, there were no ill
> effects on my testbox. Perhaps we should mirror
> /proc/sys/kernel/sched_schedstats and provide a delayacct sysctl for runtime
> frobbing.
>

There are tools like iotop that use delayacct to display information. When the
code was checked in, we did run SPEC* back in the day 2006 to find overheads,
nothing significant showed. Do we have any date on the overhead your seeing?

I'll look at the patches

Balbir Singh. 

  parent reply	other threads:[~2021-05-05 22:29 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05 10:59 [PATCH 0/6] sched,delayacct: Some cleanups Peter Zijlstra
2021-05-05 10:59 ` [PATCH 1/6] delayacct: Use sched_clock() Peter Zijlstra
2021-05-05 14:40   ` Rik van Riel
2021-05-06 13:59   ` Johannes Weiner
2021-05-06 14:17     ` Peter Zijlstra
2021-05-06 15:17       ` Johannes Weiner
2021-05-07 12:40   ` Balbir Singh
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 10:43   ` [PATCH 1/6] " Mel Gorman
2021-05-05 10:59 ` [PATCH 2/6] sched: Rename sched_info_{queued,dequeued} Peter Zijlstra
2021-05-05 14:39   ` Rik van Riel
2021-05-06 13:59   ` Johannes Weiner
2021-05-10  8:45   ` Balbir Singh
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 10:49   ` [PATCH 2/6] " Mel Gorman
2021-05-05 10:59 ` [PATCH 3/6] sched: Simplify sched_info_on() Peter Zijlstra
2021-05-06 14:03   ` Johannes Weiner
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:10   ` [PATCH 3/6] " Mel Gorman
2021-05-12 11:32     ` Peter Zijlstra
2021-05-12 12:51       ` Mel Gorman
2021-05-05 10:59 ` [PATCH 4/6] kvm: Select SCHED_INFO instead of TASK_DELAY_ACCT Peter Zijlstra
2021-05-05 11:37   ` Paolo Bonzini
2021-05-06 14:38   ` Marc Zyngier
2021-05-07 12:42   ` Balbir Singh
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:11   ` [PATCH 4/6] " Mel Gorman
2021-05-05 10:59 ` [PATCH 5/6] delayacct: Add static_branch in scheduler hooks Peter Zijlstra
2021-05-06 14:05   ` Johannes Weiner
2021-05-10  8:42   ` Balbir Singh
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:13   ` [PATCH 5/6] " Mel Gorman
2021-05-05 10:59 ` [PATCH 6/6] [RFC] delayacct: Default disabled Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:35   ` [PATCH 6/6] [RFC] " Mel Gorman
2021-05-05 22:29 ` Balbir Singh [this message]
2021-05-06  9:13   ` [PATCH 0/6] sched,delayacct: Some cleanups Peter Zijlstra
2021-05-07 12:38     ` Balbir Singh
2021-05-12 11:34       ` Mel Gorman
2021-05-12 11:38         ` Peter Zijlstra
2021-05-12 12:23         ` Paul Wise
2021-05-12 13:00           ` Mel Gorman
2021-05-13  1:29             ` Paul Wise
2021-06-25  0:50         ` Paul Wise
2021-05-07  9:05 ` Thomas Gleixner
2021-05-10  7:08 ` Ingo Molnar
2021-05-10 12:05 ` [PATCH 7/6] delayacct: Add sysctl to enable at runtime Peter Zijlstra
2021-05-10 12:06   ` Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:40   ` [PATCH 7/6] " Mel Gorman
2021-05-19  8:09     ` [tip: sched/core] delayacct: Document task_delayacct sysctl tip-bot2 for Mel Gorman

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