From: Matthew Wilcox <matthew@wil.cx>
To: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: Benjamin <bcrl@kvack.org>,
linux-aio@kvack.org, fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] aio: optimize free kioctx slot search
Date: Fri, 27 Dec 2013 05:32:50 -0700 [thread overview]
Message-ID: <20131227123250.GA22587@parisc-linux.org> (raw)
In-Reply-To: <52BD5738.4010308@cn.fujitsu.com>
On Fri, Dec 27, 2013 at 06:32:24PM +0800, Gu Zheng wrote:
> Hi Matthew,
> On 12/26/2013 10:13 PM, Matthew Wilcox wrote:
>
> > On Thu, Dec 26, 2013 at 06:22:10PM +0800, Gu Zheng wrote:
> >> to the new free slot if it's smaller than 'next_free'. So that we can
> >> ensure that the slots before 'next_free' are all used, and the search can start
> >> from 'next_free' to reduce the search and improve the performance.
> >
> > Have you benchmarked it? What kinds of improvements are you seeing?
>
> Not yet. But the improvement is obvious, we can always reduce the search region and
> improve the hit rate when trying to find a free slot with this change.
It's not so obvious to me. You've added extra stores, which may dirty
an additional cacheline. That may end up costing more than it saves.
I suspect the difference is lost in the noise, but I've been wrong about
these things before.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
prev parent reply other threads:[~2013-12-27 12:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-26 10:22 [PATCH] aio: optimize free kioctx slot search Gu Zheng
2013-12-26 10:22 ` Gu Zheng
2013-12-26 10:39 ` Miao Xie
2013-12-26 10:39 ` Miao Xie
2013-12-26 14:13 ` Matthew Wilcox
2013-12-27 10:32 ` Gu Zheng
2013-12-27 10:32 ` Gu Zheng
2013-12-27 12:32 ` Matthew Wilcox [this message]
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