From: xinhui <xinhui.pan@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, waiman.long@hpe.com
Subject: Re: [PATCH] locking/qspinlock: Use this_cpu_ptr instead of this_cpu_dec
Date: Mon, 06 Jun 2016 11:21:13 +0800 [thread overview]
Message-ID: <5754EC29.2090503@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160603113703.GK3190@twins.programming.kicks-ass.net>
On 2016年06月03日 19:37, Peter Zijlstra wrote:
> On Fri, Jun 03, 2016 at 05:48:50PM +0800, Pan Xinhui wrote:
>> queued_spin_lock_slowpath should not worry about interrupt change
>> node->count by accident because ->count is inc and dec when we
>> enter/leave queued_spin_lock_slowpath.
>>
>> So this_cpu_dec() does some no point things here, lets use this_cpu_ptr
>> for a small optimization.
>
> Uhm, have you actually looked at what that does on x86?
>
yep, just one instruction inc/dec.
well, with my patch, there are two instructions.
next prev parent reply other threads:[~2016-06-06 3:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-03 9:48 [PATCH] locking/qspinlock: Use this_cpu_ptr instead of this_cpu_dec Pan Xinhui
2016-06-03 11:37 ` Peter Zijlstra
2016-06-06 3:21 ` xinhui [this message]
2016-06-03 21:20 ` Waiman Long
2016-06-03 21:35 ` Peter Zijlstra
2016-06-06 4:48 ` xinhui
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