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Message-ID: <Pine.LNX.4.64.0708081824070.9909@asgard.lang.hm>
Date: Wed, 8 Aug 2007 18:26:24 -0700 (PDT)
From: david@...g.hm
To: Greg Trounson <gregt@...hs.otago.ac.nz>
cc: Ingo Molnar <mingo@...e.hu>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/23] per device dirty throttling -v8
On Thu, 9 Aug 2007, Greg Trounson wrote:
>> Measurements show that noatime helps 20-30% on regular desktop workloads,
>> easily 50% for kernel builds and much more than that (in excess of 100%)
>> for file-read-intense workloads. We cannot just walk past such a _huge_
>> performance impact so easily without even reacting to the performance
>> arguments, and i'm happy Ubuntu picked up noatime,nodiratime and is
>> whipping up the floor with Fedora on the desktop.
>>
>
> Sorry I'm just not seeing those gains here. With my filesystems mounted with
> atime defaults the Quake sources build in 1m28.856s. A test with ls -ltu
> verifies that atime is working as expected. When I remount my filesystems
> with:
> mount [fs] -o remount,noatime,nodiratime
> I get a compile time of 1m23.368s, a mere 6% improvement.
>
> This is on a dual-core Athlon 4200+ box running 2.6.21, so I would have
> thought this to be close to a best-case file I/O test.
what sort of disks does this box have? and what filesystem? slower
disks/filesystems can result in this showing a larger difference.
however 6% is a fairly significant gain.
David Lang
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