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From: Davidlohr Bueso <dave@stgolabs.net>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Darren Hart <darren@dvhart.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	fredrik.markstrom@windriver.com,
	Manfred Spraul <manfred@colorfullife.com>
Subject: Re: [PATCH 2/3 v2] futex: avoid double wake up in futex_wake() on -RT
Date: Sun, 12 Apr 2015 20:02:35 -0700	[thread overview]
Message-ID: <1428894155.16668.6.camel@stgolabs.net> (raw)
In-Reply-To: <20150410161135.GF3057@linutronix.de>

On Fri, 2015-04-10 at 18:11 +0200, Sebastian Andrzej Siewior wrote:
> This patch delays the wakeup of the process untill
						^^^ until

>  the hb->lock is
> dropped to avoid boosting + context switch to obtain the lock.

Doing the wakeups while holding the lock is also a general performance
issue for futex_wake. The problem being dealing with spurious wakeups
(wacky drivers), which makes no difference wrt nr_wake.

Thanks,
Davidlohr


  reply	other threads:[~2015-04-13  3:03 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-07 15:03 improve futex on -RT by avoiding the double wake-up Sebastian Andrzej Siewior
2015-04-07 15:03 ` [PATCH 1/3] futex: avoid double wake up in PI futex wait / wake on -RT Sebastian Andrzej Siewior
2015-04-07 18:41   ` Thomas Gleixner
2015-04-10 14:42     ` [PATCH 1/3 v2] " Sebastian Andrzej Siewior
2015-04-07 15:03 ` [PATCH 2/3] futex: avoid double wake up in futex_wake() " Sebastian Andrzej Siewior
2015-04-07 19:47   ` Thomas Gleixner
2015-04-10 16:11     ` [PATCH 2/3 v2] " Sebastian Andrzej Siewior
2015-04-13  3:02       ` Davidlohr Bueso [this message]
2015-04-16  5:09         ` Davidlohr Bueso
2015-04-16  9:19           ` Thomas Gleixner
2015-04-16 10:16             ` Peter Zijlstra
2015-04-16 10:49               ` Thomas Gleixner
2015-04-16 14:42               ` Davidlohr Bueso
2015-04-16 15:54                 ` Peter Zijlstra
2015-04-16 16:22                   ` Davidlohr Bueso
2015-04-07 15:03 ` [PATCH 3/3] ipc/mqueue: remove STATE_PENDING Sebastian Andrzej Siewior
2015-04-07 17:48   ` Manfred Spraul
2015-04-07 18:28     ` Thomas Gleixner
2015-04-10 14:37     ` [PATCH v2] " Sebastian Andrzej Siewior
2015-04-23 22:18       ` Thomas Gleixner
2015-04-28  3:24         ` Davidlohr Bueso
2015-04-28 12:37           ` Peter Zijlstra
2015-04-28 16:36             ` Davidlohr Bueso
2015-04-28 16:43               ` Peter Zijlstra
2015-04-28 16:59                 ` Davidlohr Bueso
2015-04-29 19:44                   ` Manfred Spraul
2015-04-30 18:46                     ` Davidlohr Bueso

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