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From: Jason Low <jason.low2@hp.com>
To: paulmck@linux.vnet.ibm.com
Cc: mingo@redhat.com, peterz@infradead.org, Waiman.Long@hp.com,
	torvalds@linux-foundation.org, tglx@linutronix.de,
	linux-kernel@vger.kernel.org, riel@redhat.com,
	akpm@linux-foundation.org, davidlohr@hp.com, hpa@zytor.com,
	andi@firstfloor.org, aswin@hp.com, scott.norton@hp.com,
	chegu_vinod@hp.com
Subject: Re: [PATCH v2 1/5] mutex: In mutex_can_spin_on_owner(), return false if task need_resched()
Date: Tue, 28 Jan 2014 14:01:00 -0800	[thread overview]
Message-ID: <1390946460.2807.19.camel@j-VirtualBox> (raw)
In-Reply-To: <20140128202042.GN9012@linux.vnet.ibm.com>

On Tue, 2014-01-28 at 12:20 -0800, Paul E. McKenney wrote:
> On Tue, Jan 28, 2014 at 11:13:12AM -0800, Jason Low wrote:
> > The mutex_can_spin_on_owner() function should also return false if the
> > task needs to be rescheduled to avoid entering the MCS queue when it
> > needs to reschedule.
> > 
> > Signed-off-by: Jason Low <jason.low2@hp.com>
> 
> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
> But I cannot help asking how this affects performance.  (My guess is
> "not much", but always good to know.)

Hi Paul,

In the past, when I tested this particular patch, I did not see any
noticeable performance gains. Patch 1 is really more of a "correctness"
change which was why I didn't retest this by itself. I can be sure to
include the benchmarks numbers on this particular patch though next
time.

Thanks.


  reply	other threads:[~2014-01-28 22:01 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-28 19:13 [PATCH v2 0/5] mutex: Mutex scalability patches Jason Low
2014-01-28 19:13 ` [PATCH v2 1/5] mutex: In mutex_can_spin_on_owner(), return false if task need_resched() Jason Low
2014-01-28 20:20   ` Paul E. McKenney
2014-01-28 22:01     ` Jason Low [this message]
2014-01-28 21:09   ` Davidlohr Bueso
2014-03-11 12:41   ` [tip:core/locking] locking/mutexes: Return false if task need_resched() in mutex_can_spin_on_owner() tip-bot for Jason Low
2014-01-28 19:13 ` [PATCH v2 2/5] mutex: Modify the way optimistic spinners are queued Jason Low
2014-01-28 20:23   ` Paul E. McKenney
2014-01-28 20:24     ` Paul E. McKenney
2014-01-28 21:17     ` Davidlohr Bueso
2014-01-28 22:10     ` Jason Low
2014-02-02 21:58       ` Paul E. McKenney
2014-03-11 12:41   ` [tip:core/locking] locking/mutexes: " tip-bot for Jason Low
2014-03-11 15:24     ` Jason Low
2014-03-11 15:33       ` Peter Zijlstra
2014-01-28 19:13 ` [PATCH v2 3/5] mutex: Unlock the mutex without the wait_lock Jason Low
2014-03-11 12:41   ` [tip:core/locking] locking/mutexes: " tip-bot for Jason Low
2014-03-12 12:24     ` Peter Zijlstra
2014-03-12 18:44       ` Jason Low
2014-03-13  7:28       ` [tip:core/locking] locking/mutex: Fix debug checks tip-bot for Peter Zijlstra
2014-01-28 19:13 ` [RFC][PATCH v2 4/5] mutex: Disable preemtion between modifying lock->owner and locking/unlocking mutex Jason Low
2014-01-28 20:54   ` Peter Zijlstra
2014-01-28 22:17     ` Jason Low
2014-01-28 19:13 ` [RFC][PATCH v2 5/5] mutex: Give spinners a chance to spin_on_owner if need_resched() triggered while queued Jason Low
2014-01-28 21:07   ` Peter Zijlstra
2014-01-28 22:51     ` Jason Low
2014-01-29 11:51       ` Peter Zijlstra
2014-01-31  3:29         ` Jason Low
2014-01-31 14:09           ` Peter Zijlstra
2014-01-31 20:01             ` Jason Low
2014-01-31 20:08               ` Peter Zijlstra
2014-02-02 21:01                 ` Jason Low
2014-02-02 21:12                   ` Peter Zijlstra
2014-02-03 18:39                     ` Jason Low
2014-02-03 19:25                       ` Peter Zijlstra
2014-02-03 20:55                         ` Jason Low
2014-02-03 21:06                           ` Peter Zijlstra
2014-02-03 21:56                             ` Jason Low
2014-02-04  7:13                         ` Jason Low
2014-02-02 22:02                 ` Paul E. McKenney
2014-02-02 20:02             ` Peter Zijlstra
2014-02-05 21:44         ` Waiman Long
2014-02-06 14:04           ` Peter Zijlstra
2014-02-06 18:45             ` Waiman Long
2014-02-06 20:10               ` Norton, Scott J
2014-02-10 17:01                 ` Peter Zijlstra
2014-02-06 17:44           ` Jason Low
2014-02-06 18:37             ` Waiman Long
2014-01-28 21:08 ` [PATCH v2 0/5] mutex: Mutex scalability patches Davidlohr Bueso
2014-01-28 23:11   ` Jason Low

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