From: Peter Zijlstra <peterz@infradead.org>
To: "Fernando Luis Vázquez Cao" <fernando_b1@lab.ntt.co.jp>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
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: Tue, 20 Aug 2013 10:44:05 +0200 [thread overview]
Message-ID: <20130820084405.GC3258@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <521313D8.9080500@lab.ntt.co.jp>
On Tue, Aug 20, 2013 at 03:59:36PM +0900, Fernando Luis Vázquez Cao wrote:
> That said, if deemed acceptable, option A is the one I would
> choose.
Right, so I think we can do A without much extra cost mostly because we
already have 2 atomics in the io_schedule() path. If we replace those
two atomic operations with locks and modify nr_iowait and the other
stats under the same lock, and ensure all those variables (including the
lock) live in the same cacheline we should have the same cost we have
now.
Of course, if we can get away with completely removing all of that
(which I think Arjan suggested was a real possibility) then that would
be ever so much better still :-)
next prev parent reply other threads:[~2013-08-20 8:44 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
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 [this message]
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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