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From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Fernando Luis Vazquez Cao <fernando_b1@lab.ntt.co.jp>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock
Date: Mon, 19 Aug 2013 12:58:17 +0200	[thread overview]
Message-ID: <20130819105817.GD24092@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20130816171208.GJ24210@somewhere>

On Fri, Aug 16, 2013 at 07:12:09PM +0200, Frederic Weisbecker wrote:
> Or may be Peter could tell us as well. Peter, do you have a preference?

Still trying to wrap my head around it, but conceptually
get_cpu_iowait_time_us() doesn't make any kind of sense. iowait isn't
per cpu since effectively tasks that aren't running aren't assigned a
cpu (as Oleg already pointed out).

The fact that cpufreq 'needs' this just means that cpufreq is broken --
but I think I've said as much previously; cpufreq needs to stop living
in the partitioned-mp era and get dragged (kicking and screaming) into
the smp era.

I'm also not entirely clear on the 'desired' semantics here. Do we count
iowait time as idle or not?

  parent reply	other threads:[~2013-08-19 10:58 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-16 15:42 [PATCH RESEND 0/4] nohz: Fix racy sleeptime stats Frederic Weisbecker
2013-08-16 15:42 ` [PATCH 1/4] nohz: Only update sleeptime stats locally Frederic Weisbecker
2013-08-18 16:49   ` Oleg Nesterov
2013-08-18 21:38     ` Frederic Weisbecker
2013-08-18 17:04   ` Oleg Nesterov
2013-08-19 18:05     ` Stratos Karafotis
2013-08-16 15:42 ` [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock Frederic Weisbecker
2013-08-16 16:02   ` Oleg Nesterov
2013-08-16 16:20     ` Frederic Weisbecker
2013-08-16 16:26       ` Oleg Nesterov
2013-08-16 16:46         ` Frederic Weisbecker
2013-08-16 16:49           ` Oleg Nesterov
2013-08-16 17:12             ` Frederic Weisbecker
2013-08-18 16:36               ` Oleg Nesterov
2013-08-18 21:25                 ` Frederic Weisbecker
2013-08-19 10:58               ` Peter Zijlstra [this message]
2013-08-19 15:44                 ` Arjan van de Ven
2013-08-19 15:47                 ` Arjan van de Ven
2013-08-19 11:10           ` Peter Zijlstra
2013-08-19 11:15             ` Peter Zijlstra
2013-08-20  6:59             ` Fernando Luis Vázquez Cao
2013-08-20  8:44               ` Peter Zijlstra
2013-08-20 15:29                 ` Frederic Weisbecker
2013-08-20 15:33                   ` Arjan van de Ven
2013-08-20 15:35                     ` Frederic Weisbecker
2013-08-20 15:41                       ` Arjan van de Ven
2013-08-20 15:31                 ` Arjan van de Ven
2013-08-20 16:01                   ` Peter Zijlstra
2013-08-20 16:33                     ` Oleg Nesterov
2013-08-20 17:54                       ` Peter Zijlstra
2013-08-20 18:25                         ` Oleg Nesterov
2013-08-21  8:31                           ` Peter Zijlstra
2013-08-21 11:35                             ` Oleg Nesterov
2013-08-21 12:33                               ` Peter Zijlstra
2013-08-21 14:23                                 ` Peter Zijlstra
2013-08-21 16:41                                   ` Oleg Nesterov
2013-10-01 14:05                                     ` Frederic Weisbecker
2013-10-01 14:26                                       ` Frederic Weisbecker
2013-10-01 14:27                                         ` Frederic Weisbecker
2013-10-01 14:49                                         ` Frederic Weisbecker
2013-10-01 15:00                                       ` Peter Zijlstra
2013-10-01 15:21                                         ` Frederic Weisbecker
2013-10-01 15:56                                       ` Peter Zijlstra
2013-10-01 16:47                                         ` Frederic Weisbecker
2013-10-01 16:59                                           ` Peter Zijlstra
2013-10-02 12:45                                             ` Frederic Weisbecker
2013-10-02 12:50                                               ` Peter Zijlstra
2013-10-02 14:35                                               ` Arjan van de Ven
2013-10-02 16:01                                                 ` Frederic Weisbecker
2013-08-21 12:48                               ` Peter Zijlstra
2013-08-21 17:09                                 ` Oleg Nesterov
2013-08-21 18:31                                   ` Peter Zijlstra
2013-08-21 18:32                                     ` Oleg Nesterov
2013-08-20 22:18                       ` Frederic Weisbecker
2013-08-21 11:49                         ` Oleg Nesterov
2013-08-20  6:21           ` Fernando Luis Vázquez Cao
2013-08-20 21:55             ` Frederic Weisbecker
2013-08-16 16:32     ` Frederic Weisbecker
2013-08-16 16:33       ` Oleg Nesterov
2013-08-16 16:49         ` Frederic Weisbecker
2013-08-16 16:37       ` Frederic Weisbecker
2013-08-18 16:54   ` Oleg Nesterov
2013-08-18 21:40     ` Frederic Weisbecker
2013-08-16 15:42 ` [PATCH 3/4] nohz: Consolidate sleep time stats read code Frederic Weisbecker
2013-08-18 17:00   ` Oleg Nesterov
2013-08-18 21:47     ` Frederic Weisbecker
2013-08-16 15:42 ` [PATCH 4/4] nohz: Convert a few places to use local per cpu accesses Frederic Weisbecker
2013-08-16 16:00   ` Peter Zijlstra
2013-08-16 16:12     ` Frederic Weisbecker
2013-08-16 16:19     ` Oleg Nesterov
2013-08-16 16:34       ` Frederic Weisbecker
2013-08-20 18:15 ` [PATCH RESEND 0/4] nohz: Fix racy sleeptime stats Oleg Nesterov
2013-08-21  8:28   ` Peter Zijlstra
2013-08-21 11:42     ` Oleg Nesterov
  -- strict thread matches above, loose matches on Subject: below --
2014-05-07 13:41 [PATCH 1/4] nohz: Only update sleeptime stats locally Denys Vlasenko
2014-05-07 13:41 ` [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock Denys Vlasenko
2014-04-24 18:45 [PATCH 1/4] nohz: Only update sleeptime stats locally Denys Vlasenko
2014-04-24 18:45 ` [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock Denys Vlasenko
2013-08-09  0:54 [PATCH 0/4] nohz: Fix racy sleeptime stats Frederic Weisbecker
2013-08-09  0:54 ` [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock Frederic Weisbecker

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