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Re: [PING][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 08:49:26 +0100
Subject: Re: [PING][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>

On 12/13/2016 09:54 AM, 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?

Bye
Stefan

ChangeLog:

    * sysdeps/nptl/lowlevellock.h (lll_trylock, lll_cond_trylock):
    Add __glibc_unlikely hint.


ping

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