linux-kernel - Re: efficient access to "rotational"; new fcntl?

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Message-ID: <20090919103149.54258081@infradead.org>
Date:	Sat, 19 Sep 2009 10:31:49 +0200
From:	Arjan van de Ven <arjan@...radead.org>
To:	Jim Meyering <jim@...ering.net>
Cc:	Theodore Tso <tytso@....edu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: efficient access to "rotational";  new fcntl?

On Sat, 19 Sep 2009 10:01:51 +0200
Jim Meyering <jim@...ering.net> wrote:
> Yeah, I mentioned I should do exactly that on IRC yesterday.
> I've just run some tests, and see that at least with one SSD (OCZ
> Summit 120GB), the 0.5s cost of sorting pays off handsomely with a
> 12-x speed-up, saving 5.5 minutes, when removing a
> 1-million-empty-file directory.
> 

likely because you actually reduce the amount of IO; inodes share
disk blocks; repeated unlinks in random order likely write the same
block multiple times....


btw have you given thought about using threads as part of rm -r[f] ?
(would make the unlinks of unrelated directories/files asynchronous)

-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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