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From: Ingo Molnar <mingo@kernel.org>
To: Alex Shi <alex.shi@intel.com>
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: Tue, 5 Feb 2013 15:58:54 +0100	[thread overview]
Message-ID: <20130205145854.GA30949@gmail.com> (raw)
In-Reply-To: <1360069915-31619-1-git-send-email-alex.shi@intel.com>


* 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?

Thanks,

	Ingo

  reply	other threads:[~2013-02-05 14:59 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 [this message]
2013-02-06  0:07   ` Alex Shi
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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