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From: Tejun Heo <tj@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Jens Axboe <axboe@kernel.dk>, Ingo Molnar <mingo@elte.hu>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [patch 4/4] sched: Distangle worker accounting from rq->lock
Date: Thu, 23 Jun 2011 10:37:22 +0200	[thread overview]
Message-ID: <20110623083722.GF30101@htj.dyndns.org> (raw)
In-Reply-To: <20110622174919.135236139@linutronix.de>

Hello, Thomas.

The hooking place doesn't have anything to do with rq->lock.  The
problem with Peter's patch was preemption, not the lock.

> There is also no harm from updating nr_running when the task returns
> from scheduling instead of accounting it in the wakeup code.

Well, not exactly.  If CPU is being thrashed, we don't want to try to
fire up new workers or calling in rescuers.  If nr_running is bumped
up from ttwu(), a woken up but not yet running worker already counts
as running.  With the suggested change, when we hit such heavy CPU
thrashing, workqueue code will add things on top of it.

Thanks.

-- 
tejun

  parent reply	other threads:[~2011-06-23  8:37 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-22 17:52 [patch 0/4] sched: Move work out of the scheduler core Thomas Gleixner
2011-06-22 17:52 ` [patch 1/4] sched: Separate the scheduler entry for preemption Thomas Gleixner
2011-06-22 18:43   ` Christoph Hellwig
2011-06-22 18:52     ` Thomas Gleixner
2011-06-22 19:42     ` Jens Axboe
2011-06-22 20:15       ` Thomas Gleixner
2011-06-23 11:41         ` Jens Axboe
2011-08-29 14:55   ` [tip:sched/urgent] " tip-bot for Thomas Gleixner
2011-06-22 17:52 ` [patch 3/4] block: Shorten interrupt disabled regions Thomas Gleixner
2011-06-22 17:52 ` [patch 2/4] sched: Move blk_schedule_flush_plug() out of __schedule() Thomas Gleixner
2011-06-22 17:52 ` [patch 4/4] sched: Distangle worker accounting from rq->lock Thomas Gleixner
2011-06-22 19:30   ` Thomas Gleixner
2011-06-23  8:37   ` Tejun Heo [this message]
2011-06-23  9:58     ` Thomas Gleixner
2011-06-23 10:15       ` Tejun Heo
2011-06-23 10:44         ` Ingo Molnar
2011-06-23 11:35           ` Tejun Heo
2011-06-23 12:51             ` Ingo Molnar
2011-06-24  9:01             ` Thomas Gleixner
2011-06-26 10:19               ` Tejun Heo
2011-06-23 15:07   ` Tejun Heo
2013-04-30 13:37   ` Steven Rostedt
2013-04-30 22:47     ` Steven Rostedt
2013-05-03  0:12       ` Tejun Heo
2013-05-03  0:57         ` Steven Rostedt
2013-07-24 10:04           ` Thomas Gleixner
2013-08-06 19:33             ` Steven Rostedt

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