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Subject: Re: [PATCH v2 02/11] locking/ww_mutex: Re-check ww->ctx in the inner
 optimistic spin loop
To: Peter Zijlstra <peterz@infradead.org>
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From: Waiman Long <longman@redhat.com>
Organization: Red Hat
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Date: Tue, 6 Dec 2016 13:46:42 -0500
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On 12/06/2016 01:29 PM, Peter Zijlstra wrote:
> On Tue, Dec 06, 2016 at 11:03:28AM -0500, Waiman Long wrote:
>> The mutex_spin_on_owner() function was originally marked noinline
>> because it could be a major consumer of CPU cycles in a contended lock.
>> Having it shown separately in the perf output will help the users have a
>> better understanding of what is consuming all the CPU cycles. So I would
>> still like to keep it this way.
> ah!, I tried to dig through history but couldn't find a reason for it.
>
>> If you have concern about additional latency for non-ww_mutex calls, one
>> alternative can be:
> That's pretty horrific :/

I am not totally against making mutex_spin_on_owner() an inline
function. If you think it is the right way to go, I am OK with that.

-Longman