linux-kernel - Re: Ext4 and the "30 second window of death"

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Message-ID: <20090401212600.GA18301@srcf.ucam.org>
Date:	Wed, 1 Apr 2009 22:26:00 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Ray Lee <ray-lk@...rabbit.org>
Cc:	Theodore Tso <tytso@....edu>, Sitsofe Wheeler <sitsofe@...oo.com>,
	"Andreas T.Auer" <andreas.t.auer_lkml_73537@...us.ath.cx>,
	Alberto Gonzalez <info@...bu.es>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Ext4 and the "30 second window of death"

On Wed, Apr 01, 2009 at 02:21:43PM -0700, Ray Lee wrote:
> On Wed, Apr 1, 2009 at 10:43 AM, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> > I've got absolutely no idea why anyone would want fsync() to stop
> > meaning "Put my data on the disk please".
> 
> Some guy named Andrew used to run a kernel with 'return 0' at the top
> of fsync and fdatasync: http://lkml.org/lkml/2007/4/27/88
> 
> It's that the latency penalty of apps using *sync() on common hardware
> sucks. That's all, and finding a way to fix that would make this
> entire thread go away, I think.

And also disk spinups.
-- 
Matthew Garrett | mjg59@...f.ucam.org
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