From: Peter Zijlstra <peterz@infradead.org>
To: Pan Xinhui <xinhui@linux.vnet.ibm.com>
Cc: Waiman Long <longman@redhat.com>, Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [PATCH v2] locking/pvqspinlock: Relax cmpxchg's to improve performance on some archs
Date: Thu, 5 Jan 2017 10:48:53 +0100 [thread overview]
Message-ID: <20170105094853.GE3093@worktop> (raw)
In-Reply-To: <006322ad-2e72-c8fe-361f-233f1821063a@linux.vnet.ibm.com>
On Thu, Jan 05, 2017 at 04:16:38PM +0800, Pan Xinhui wrote:
> I do some tests about cmpxchg and cmpxchg_acquire before on ppc.
>
> loops in 15s of each cmpxchg is below.
>
> cmpxchg_relaxed: 336663
> cmpxchg_release: 369054
> cmpxchg_acquire: 363364
> cmpxchg: 179435
>
> so cmpxchg is really expensive than others.
> but I also have doubt about the cmpxchg_relaxed, it should be the cheapest, but from the tests, release/acquire are faster than it.
Right, curious about that relaxed one. In any case, I was more wondering
about the performance impact on the larger construct of the pvlock
itself.
next prev parent reply other threads:[~2017-01-05 9:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-25 20:26 [PATCH v2] locking/pvqspinlock: Relax cmpxchg's to improve performance on some archs Waiman Long
2016-12-26 5:50 ` Boqun Feng
2017-01-03 22:23 ` Waiman Long
2017-01-03 16:18 ` Peter Zijlstra
2017-01-03 22:07 ` Waiman Long
2017-01-04 9:41 ` Peter Zijlstra
2017-01-05 8:16 ` Pan Xinhui
2017-01-05 9:48 ` Peter Zijlstra [this message]
2017-01-05 9:51 ` Boqun Feng
2017-01-05 15:17 ` Waiman Long
2017-01-05 15:40 ` Boqun Feng
2017-01-05 15:30 ` Waiman Long
[not found] ` <CAH4ORazqsCBA4G5paHtsp8PMfM=J3P6rvyR-53-ZLjn=7U6J0g@mail.gmail.com>
2017-02-08 4:05 ` Boqun Feng
2017-02-08 6:09 ` Boqun Feng
2017-02-08 6:47 ` Pan Xinhui
2017-02-08 6:48 ` Pan Xinhui
2017-02-08 7:09 ` Pan Xinhui
2017-02-08 7:15 ` Boqun Feng
[not found] ` <778926a5-cf9f-586b-6bc4-b9453d88aabb@redhat.com>
2017-02-13 2:24 ` panxinhui
2017-02-13 3:19 ` Boqun Feng
2017-02-17 19:01 ` Waiman Long
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