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Re: [PATCH] Add __glibc_unlikely hint in lll_trylock, lll_cond_trylock.

From: Stefan Liebler <stli at linux dot vnet dot ibm dot com>
To: libc-alpha at sourceware dot org
Date: Mon, 6 Feb 2017 13:49:55 +0100
Subject: Re: [PATCH] Add __glibc_unlikely hint in lll_trylock, lll_cond_trylock.
Authentication-results: sourceware.org; auth=none
References: <4adc080f-9975-4ee0-003e-675f3c9f1203@linux.vnet.ibm.com> <345086fd-2d8a-a688-44b3-780dc83d4e9c@gotplt.org>

On 02/06/2017 09:33 AM, Siddhesh Poyarekar wrote:

On Tuesday 13 December 2016 02:24 PM, Stefan Liebler wrote:

Hi,

the macros lll_trylock, lll_cond_trylock are extended by a
__glibc_unlikely hint. Now the trylock macros are based on the
same assumption about a free/busy lock as lll_lock.
With the hint gcc emits code in e.g. pthread_mutex_trylock which does
not use jumps if the lock is free.  Without the hint it had to jump away
if the lock is free.

Tested on s390x, ppc.

Okay to commit?


Yes, looks good.

Siddhesh

Thanks. Committed.

References:
- Re: [PATCH] Add __glibc_unlikely hint in lll_trylock, lll_cond_trylock.
  - From: Siddhesh Poyarekar

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