From: Davidlohr Bueso <dave@stgolabs.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics
Date: Tue, 15 Sep 2015 12:49:46 -0700 [thread overview]
Message-ID: <20150915194945.GI19736@linux-q0g1.site> (raw)
In-Reply-To: <20150915095512.GA18673@twins.programming.kicks-ass.net>
On Tue, 15 Sep 2015, Peter Zijlstra wrote:
>> Secondly, the wake queues are not concurrent, they're in context, so I
>> don't see ordering matter at all. The only reason its a cmpxchg() is
>> because there is the (small) possibility of two contexts wanting to wake
>> the same task, and we use task_struct storage for the queue.
>
>I don't think we need _any_ barriers here, unless we have concurrent
>users of the wake queues (or want to allow any, do we?).
Exactly, the queues are not concurent and do not need barriers, but some of
our callers do expect them.
next prev parent reply other threads:[~2015-09-15 19:49 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-14 7:37 [PATCH -tip 1/3] locking/qrwlock: Rename ->lock to ->wait_lock Davidlohr Bueso
2015-09-14 7:37 ` [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Davidlohr Bueso
2015-09-14 12:32 ` Peter Zijlstra
2015-09-14 21:08 ` Davidlohr Bueso
2015-09-15 9:49 ` Peter Zijlstra
2015-09-15 9:55 ` Peter Zijlstra
2015-09-15 12:41 ` Paul E. McKenney
2015-09-15 12:48 ` Peter Zijlstra
2015-09-15 14:09 ` Paul E. McKenney
2015-09-15 14:14 ` Peter Zijlstra
2015-09-15 15:34 ` Paul E. McKenney
2015-09-15 16:30 ` Peter Zijlstra
2015-09-15 17:09 ` Paul E. McKenney
2015-09-18 21:41 ` Paul E. McKenney
2015-09-21 9:22 ` Martin Schwidefsky
2015-09-22 10:27 ` Martin Schwidefsky
2015-09-22 12:23 ` Boqun Feng
2015-09-22 12:51 ` Martin Schwidefsky
2015-09-22 13:29 ` Boqun Feng
2015-09-22 14:33 ` Martin Schwidefsky
2015-09-22 15:28 ` Paul E. McKenney
2015-09-23 6:43 ` Martin Schwidefsky
2015-09-25 21:30 ` Paul E. McKenney
2015-09-15 19:49 ` Davidlohr Bueso [this message]
2015-09-16 9:01 ` Peter Zijlstra
2015-09-14 7:37 ` [PATCH -tip 3/3] locking/osq: Relax atomic semantics Davidlohr Bueso
2015-09-18 8:50 ` [tip:locking/core] " tip-bot for Davidlohr Bueso
2015-09-18 8:50 ` [tip:locking/core] locking/qrwlock: Rename ->lock to ->wait_lock tip-bot for Davidlohr Bueso
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