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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 2/5] mutex: Modify the way optimistic spinners are queued
Date: Tue, 28 Jan 2014 14:10:41 -0800	[thread overview]
Message-ID: <1390947041.2807.28.camel@j-VirtualBox> (raw)
In-Reply-To: <20140128202334.GO9012@linux.vnet.ibm.com>

On Tue, 2014-01-28 at 12:23 -0800, Paul E. McKenney wrote:
> On Tue, Jan 28, 2014 at 11:13:13AM -0800, Jason Low wrote:
> >  		/*
> >  		 * The cpu_relax() call is a compiler barrier which forces
> > @@ -514,6 +511,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
> >  		 */
> >  		arch_mutex_cpu_relax();
> >  	}
> > +	mspin_unlock(MLOCK(lock), &node);
> >  slowpath:
> 
> Are there any remaining goto statements to slowpath?  If so, they need
> to release the lock.  If not, this label should be removed.

Yes, if the mutex_can_spin_on_owner() returns false, then the thread
goes to directly slowpath, bypassing the optimistic spinning loop. In
that case, the thread avoids acquiring the MCS lock, and doesn't unlock
the MCS lock.

Thanks,
Jason


  parent reply	other threads:[~2014-01-28 22:10 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
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 [this message]
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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