From: Peter Zijlstra <peterz@infradead.org>
To: Kirill Tkhai <ktkhai@parallels.com>
Cc: linux-kernel@vger.kernel.org, pjt@google.com, oleg@redhat.com,
rostedt@goodmis.org, umgwanakikbuti@gmail.com, tkhai@yandex.ru,
tim.c.chen@linux.intel.com, mingo@kernel.org,
nicolas.pitre@linaro.org
Subject: Re: [PATCH v4 4/6] sched: Remove double_rq_lock() from __migrate_task()
Date: Tue, 12 Aug 2014 10:21:20 +0200 [thread overview]
Message-ID: <20140812082120.GO9918@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1407312387.8424.40.camel@tkhai>
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On Wed, Aug 06, 2014 at 12:06:27PM +0400, Kirill Tkhai wrote:
>
> Let's use ONRQ_MIGRATING instead.
I feel there should be a little more in the changelog; how about
something like:
Avoid double_rq_lock() and use ONRQ_MIGRATING for __migrate_task(). The
advantage is (obviously) not holding two 'rq->lock's at the same time
and thereby increasing parallelism.
The important point to note is that because we acquire dst->lock
immediately after releasing src->lock the potential wait time of
task_rq_lock() callers on ONRQ_MIGRATING is not longer than it would
have been in the double rq lock scenario.
> Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
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next prev parent reply other threads:[~2014-08-12 8:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140806075138.24858.23816.stgit@tkhai>
2014-08-06 8:06 ` [PATCH v4 1/6] sched/fair: Fix reschedule which is generated on throttled cfs_rq Kirill Tkhai
2014-08-20 8:20 ` [tip:sched/core] " tip-bot for Kirill Tkhai
2014-10-23 23:27 ` [PATCH v4 1/6] " Wanpeng Li
2014-10-24 6:01 ` Kirill Tkhai
2014-10-24 9:32 ` Wanpeng Li
2014-10-24 15:12 ` Kirill Tkhai
2014-08-06 8:06 ` [PATCH v4 2/6] sched: Wrapper for checking task_struct::on_rq Kirill Tkhai
2014-08-20 7:52 ` Ingo Molnar
2014-08-06 8:06 ` [PATCH v4 3/6] sched: Teach scheduler to understand ONRQ_MIGRATING state Kirill Tkhai
2014-08-12 7:55 ` Peter Zijlstra
2014-08-12 8:34 ` Kirill Tkhai
2014-08-12 9:43 ` Peter Zijlstra
2014-08-06 8:06 ` [PATCH v4 4/6] sched: Remove double_rq_lock() from __migrate_task() Kirill Tkhai
2014-08-12 8:21 ` Peter Zijlstra [this message]
2014-08-06 8:06 ` [PATCH v4 5/6] sched/fair: Remove double_lock_balance() from active_load_balance_cpu_stop() Kirill Tkhai
2014-08-12 9:03 ` Peter Zijlstra
2014-08-12 9:22 ` Peter Zijlstra
2014-08-12 9:39 ` Kirill Tkhai
2014-08-06 8:07 ` [PATCH v4 6/6] sched/fair: Remove double_lock_balance() from load_balance() Kirill Tkhai
2014-08-12 9:36 ` Peter Zijlstra
2014-08-12 10:27 ` Kirill Tkhai
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