From: Peter Zijlstra <peterz@infradead.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, waiman.long@hpe.com,
mingo@redhat.com, paulmck@linux.vnet.ibm.com,
torvalds@linux-foundation.org, dave@stgolabs.net
Subject: Re: [RFC][PATCH 3/3] locking,arm64: Introduce cmpwait()
Date: Sat, 23 Apr 2016 04:37:36 +0200 [thread overview]
Message-ID: <20160423023736.GZ3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160422160857.GA3369@insomnia>
On Sat, Apr 23, 2016 at 12:08:57AM +0800, Boqun Feng wrote:
> How about replace smp_rmb() with a smp_acquire_barrier__after_cmpwait()?
> This barrier is designed to provide an ACQUIRE ordering when combining a
> cmpwait() .
That's a horrible name for a barrier :-)
> And cmpwait() only has minimal ordering guarantee, but if it is actually
> an ACQUIRE, then the corresponding smp_acquire_barrier__after_cmpwait()
> is just empty.
>
> We might need this special barrier on ppc, because we can implement it
> with "isync" given that cmpwait() has control dependency and ctrl+isync
> is ACQUIRE on ppc.
>
> Thoughts?
Provide a PPC specific smp_cond_load_acquire() using ISYNC ?
next prev parent reply other threads:[~2016-04-23 2:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 12:22 [RFC][PATCH 0/3] smp_cond_load_acquire + cmpwait Peter Zijlstra
2016-04-04 12:22 ` [RFC][PATCH 1/3] locking: Replace smp_cond_acquire with smp_cond_load_acquire Peter Zijlstra
2016-04-04 18:20 ` Waiman Long
2016-04-04 12:22 ` [RFC][PATCH 2/3] locking/qrwlock: Use smp_cond_load_acquire() Peter Zijlstra
2016-04-12 4:58 ` Davidlohr Bueso
2016-04-12 16:45 ` Waiman Long
2016-04-04 12:22 ` [RFC][PATCH 3/3] locking,arm64: Introduce cmpwait() Peter Zijlstra
2016-04-04 13:12 ` Peter Zijlstra
2016-04-12 16:59 ` Will Deacon
2016-04-13 12:52 ` Peter Zijlstra
2016-04-26 16:33 ` Will Deacon
2016-04-26 17:15 ` Will Deacon
2016-04-26 20:25 ` Peter Zijlstra
2016-04-22 16:08 ` Boqun Feng
2016-04-22 16:53 ` Will Deacon
2016-04-23 4:02 ` Boqun Feng
2016-04-23 2:37 ` Peter Zijlstra [this message]
2016-04-23 3:40 ` Boqun Feng
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