From: Jason Low <jason.low2@hp.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Waiman Long <waiman.long@hp.com>,
mingo@kernel.org, paulmck@linux.vnet.ibm.com,
torvalds@linux-foundation.org, tglx@linutronix.de,
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 5/8] locking, mutex: Cancelable MCS lock for adaptive spinning
Date: Wed, 26 Feb 2014 09:45:25 -0800 [thread overview]
Message-ID: <1393436725.11382.3.camel@j-VirtualBox> (raw)
In-Reply-To: <20140226092210.GH18404@twins.programming.kicks-ass.net>
On Wed, 2014-02-26 at 10:22 +0100, Peter Zijlstra wrote:
> On Tue, Feb 25, 2014 at 11:56:19AM -0800, Jason Low wrote:
> > On Mon, 2014-02-10 at 20:58 +0100, Peter Zijlstra wrote:
> > > + for (;;) {
> > > + if (prev->next == node &&
> > > + cmpxchg(&prev->next, node, NULL) == node)
> > > + break;
> > > +
> > > + /*
> > > + * We can only fail the cmpxchg() racing against an unlock(),
> > > + * in which case we should observe @node->locked becomming
> > > + * true.
> > > + */
> > > + if (smp_load_acquire(&node->locked))
> > > + return true;
>
> I've stuck on in right about here. So that we don't unduly delay the
> cmpxchg() after the load of prev.
Ok.
Reviewed-by: Jason Low <jason.low2@hp.com>
next prev parent reply other threads:[~2014-02-26 17:45 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-10 19:58 [PATCH 0/8] locking/core patches Peter Zijlstra
2014-02-10 19:58 ` [PATCH 1/8] locking: Move mcs_spinlock.h into kernel/locking/ Peter Zijlstra
2014-02-10 19:58 ` [PATCH 2/8] mutex: In mutex_can_spin_on_owner(), return false if task need_resched() Peter Zijlstra
2014-02-10 21:02 ` Peter Zijlstra
2014-02-10 19:58 ` [PATCH 3/8] mutex: Modify the way optimistic spinners are queued Peter Zijlstra
2014-02-11 1:33 ` Jason Low
2014-02-11 7:20 ` Peter Zijlstra
2014-02-10 19:58 ` [PATCH 4/8] mutex: Unlock the mutex without the wait_lock Peter Zijlstra
2014-02-10 19:58 ` [PATCH 5/8] locking, mutex: Cancelable MCS lock for adaptive spinning Peter Zijlstra
2014-02-10 21:15 ` Jason Low
2014-02-10 21:32 ` Peter Zijlstra
2014-02-10 22:04 ` Jason Low
2014-02-11 9:18 ` Peter Zijlstra
2014-02-11 9:38 ` Ingo Molnar
2014-02-25 19:56 ` Jason Low
2014-02-26 9:22 ` Peter Zijlstra
2014-02-26 17:45 ` Jason Low [this message]
2014-02-10 19:58 ` [PATCH 6/8] mutex: Extra reschedule point Peter Zijlstra
2014-02-10 22:59 ` Andrew Morton
2014-02-10 19:58 ` [PATCH 7/8] locking: Introduce qrwlock Peter Zijlstra
2014-02-11 18:17 ` Waiman Long
2014-02-11 20:12 ` Waiman Long
2014-02-13 16:35 ` Peter Zijlstra
2014-02-13 17:26 ` Peter Zijlstra
2014-02-14 19:01 ` Waiman Long
2014-02-14 18:48 ` Waiman Long
2014-02-10 19:58 ` [PATCH 8/8] x86,locking: Enable qrwlock Peter Zijlstra
2014-02-10 23:02 ` [PATCH 0/8] locking/core patches Andrew Morton
2014-02-11 7:17 ` Peter Zijlstra
2014-02-11 8:03 ` Andrew Morton
2014-02-11 8:45 ` Ingo Molnar
2014-02-11 8:57 ` Peter Zijlstra
2014-02-11 21:37 ` Waiman Long
2014-02-25 19:26 ` Jason Low
2014-02-26 21:40 ` Paul E. McKenney
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