From: Arjan van de Ven <arjan@linux.intel.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Oleg Nesterov" <oleg@redhat.com>,
"Fernando Luis Vázquez Cao" <fernando_b1@lab.ntt.co.jp>,
"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>
Subject: Re: [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock
Date: Wed, 02 Oct 2013 07:35:49 -0700 [thread overview]
Message-ID: <524C2F45.4040401@linux.intel.com> (raw)
In-Reply-To: <20131002124539.GF7941@localhost.localdomain>
On 10/2/2013 5:45 AM, Frederic Weisbecker wrote:
> On Tue, Oct 01, 2013 at 06:59:57PM +0200, Peter Zijlstra wrote:
>> On Tue, Oct 01, 2013 at 06:47:10PM +0200, Frederic Weisbecker wrote:
>>> Yeah thinking more about it, the preempt disable was probably not
>>> necessary. Now that's trading 2 atomics + 1 Lock/Unlock with 2 Lock/Unlock.
>>
>> It trades the current 2 atomics for 2 LOCK/UNLOCK. And on x86_64 that's
>> 2 atomics.
>
> Do you mean 2 atomics for LOCK/UNLOCK? Or is that pair optimized somehow
> in x86?
unlock is not actually an atomic.
and on some modern machines, neither is the lock, for the uncontended case ;-)
next prev parent reply other threads:[~2013-10-02 14:35 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
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 [this message]
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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