From: Alex Shi <alex.shi@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: torvalds@linux-foundation.org, paul.gortmaker@windriver.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rwsem: steal writing sem for better performance
Date: Wed, 06 Feb 2013 08:07:44 +0800 [thread overview]
Message-ID: <51119ED0.3030207@intel.com> (raw)
In-Reply-To: <20130205145854.GA30949@gmail.com>
On 02/05/2013 10:58 PM, Ingo Molnar wrote:
>
> * Alex Shi <alex.shi@intel.com> wrote:
>
>> Commit 5a50508 change to rwsem from mutex, that cause aim7 fork_test
>> dropped 50%. Yuanhan liu does a good analysis, find it caused by
>> strict sequential writing. Ingo suggest stealing sem writing from
>> front task in waiting queue. https://lkml.org/lkml/2013/1/29/84
>> So has this patch.
>>
>> In this patch, I just allow writing steal happen when the
>> first waiter is also writer. Then the performance fully
>> recovered.
>
> All the aim7 fork_test performance regression is recovered?
Sure. 100% recovered on my NHM EP, NHM EX, SNB EP 2S and 4S machines.
>
> Thanks,
>
> Ingo
>
--
Thanks Alex
next prev parent reply other threads:[~2013-02-06 0:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-05 13:11 [PATCH] rwsem: steal writing sem for better performance Alex Shi
2013-02-05 14:58 ` Ingo Molnar
2013-02-06 0:07 ` Alex Shi [this message]
2013-02-06 11:28 ` Ingo Molnar
2013-02-06 21:36 ` Linus Torvalds
2013-02-06 21:47 ` Ingo Molnar
2013-02-06 13:52 ` [tip:core/urgent] rwsem: Implement writer lock-stealing for better scalability tip-bot for Alex Shi
2013-02-22 12:25 ` [tip:core/locking] " tip-bot for Alex Shi
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