linux-kernel - Re: [PATCH 00/23] per device dirty throttling -v8

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Message-ID: <20070806065834.GB2818@elte.hu>
Date:	Mon, 6 Aug 2007 08:58:34 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Diego Calleja <diegocg@...il.com>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, J??rn Engel <joern@...fs.org>,
	Jeff Garzik <jeff@...zik.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, linux-mm@...ck.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	miklos@...redi.hu, akpm@...ux-foundation.org, neilb@...e.de,
	dgc@....com, tomoki.sekiyama.qu@...achi.com, nikita@...sterfs.com,
	trond.myklebust@....uio.no, yingchao.zhou@...il.com,
	richard@....demon.co.uk, david@...g.hm
Subject: Re: [PATCH 00/23] per device dirty throttling -v8


* Diego Calleja <diegocg@...il.com> 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
> 
> And as everybody knows in servers is a popular practice to disable it. 
> According to an interview to the kernel.org admins....

yeah - but i'd be surprised if more than 1% of all Linux servers out 
there had noatime.

> "Beyond that, Peter noted, "very little fancy is going on, and that is 
> good because fancy is hard to maintain." He explained that the only 
> fancy thing being done is that all filesystems are mounted noatime 
> meaning that the system doesn't have to make writes to the filesystem 
> for files which are simply being read, "that cut the load average in 
> half."

nice quote :-)

> I bet that some people would consider such performance hit a bug...

yeah.

	Ingo
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