From: Arjan van de Ven <arjan@linux.intel.com>
To: Sunil Pandey <skpgkp2@gmail.com>,
Andreas Schwab <schwab@linux-m68k.org>,
Libc-stable Mailing List <libc-stable@sourceware.org>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
Florian Weimer <fweimer@redhat.com>,
GNU C Library <libc-alpha@sourceware.org>,
"Paul A . Clarke" <pc@us.ibm.com>
Subject: Re: [PATCH v6 4/4] Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537]
Date: Sun, 11 Sep 2022 13:15:15 -0700 [thread overview]
Message-ID: <5ba017f8-b7d3-12a0-4186-d57ff48eac26@linux.intel.com> (raw)
In-Reply-To: <CAMAf5_fg4snBVbVZbuMg8G-6nep-kGxqqBoiKoiiuvPBita2dQ@mail.gmail.com>
On 9/11/2022 1:12 PM, Sunil Pandey wrote:
> On Fri, Nov 12, 2021 at 10:53 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>>
>> On Nov 11 2021, H.J. Lu wrote:
>>
>>> diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
>>> index 57f3f28869..f763cfc7fa 100644
>>> --- a/nptl/pthread_mutex_timedlock.c
>>> +++ b/nptl/pthread_mutex_timedlock.c
>>> @@ -233,12 +233,12 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
>>> meantime. */
>>> if ((oldval & FUTEX_WAITERS) == 0)
>>> {
>>> - if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
>>> - oldval | FUTEX_WAITERS,
>>> - oldval)
>>> - != 0)
>>> + int val;
>>> + if ((val = atomic_compare_and_exchange_val_acq
>>> + (&mutex->__data.__lock, oldval | FUTEX_WAITERS,
>>> + oldval)) != oldval)
>>
>> Please move the assignment out of the condition.
>>
>> Andreas.
>>
>> --
>> Andreas Schwab, schwab@linux-m68k.org
>> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
>> "And now for something completely different."
>
> I would like to backport this patch to release branch 2.33 and 2.34
>
what exactly is the stable branch policy that would suggest to backport performance improvements like this ?
(most projects are sticking to "strict bugfixes and other gross oversights" as much as possible)
next prev parent reply other threads:[~2022-09-11 20:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211111162428.2286605-1-hjl.tools@gmail.com>
[not found] ` <20211111162428.2286605-5-hjl.tools@gmail.com>
[not found] ` <87v90xryvi.fsf@igel.home>
2022-09-11 20:12 ` Sunil Pandey
2022-09-11 20:15 ` Arjan van de Ven [this message]
2022-09-11 21:26 ` Florian Weimer
2022-09-29 0:09 ` Noah Goldstein
[not found] ` <20211111162428.2286605-3-hjl.tools@gmail.com>
[not found] ` <87zgq9rywl.fsf@igel.home>
2022-09-11 20:16 ` [PATCH v6 2/4] Avoid extra load with CAS in __pthread_mutex_lock_full " Sunil Pandey
2022-09-29 0:10 ` Noah Goldstein
[not found] ` <20211111162428.2286605-2-hjl.tools@gmail.com>
[not found] ` <CAFUsyfJH45MshHkFjohENvhJzt1bC=PrUH_3xRn1KubGy9X1HA@mail.gmail.com>
[not found] ` <CAMe9rOqOv3WC9rWwtFyzc7rJFDDbNTAfTio-FZC4oW5y751FWA@mail.gmail.com>
[not found] ` <CAFUsyf+Yf=QM-0Zj31=k6fANCdXa6XnzVn=Kj6im3xDYbanbnA@mail.gmail.com>
[not found] ` <CAMe9rOpE1+1zqtA4xqJNy-RK03jXNzv-JnYSJFtGmtqSa2QqQQ@mail.gmail.com>
[not found] ` <924a80cd-202c-99e9-a2d9-1aeda2235b83@linux.intel.com>
2022-09-11 20:19 ` [PATCH v6 1/4] Add LLL_MUTEX_READ_LOCK " Sunil Pandey
2022-09-29 0:10 ` Noah Goldstein
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