From: Jeremy Higdon <jeremy@sgi.com>
To: Paul Jackson <pj@sgi.com>
Cc: Jeff Garzik <jeff@garzik.org>,
tytso@mit.edu, suparna@in.ibm.com, akpm@osdl.org, w@1wt.eu,
torvalds@osdl.org, hpa@zytor.com, git@vger.kernel.org,
nigel@nigel.suspend2.net, warthog9@kernel.org,
randy.dunlap@oracle.com, pavel@ucw.cz,
linux-kernel@vger.kernel.org, webmaster@kernel.org,
linux-ext4@vger.kernel.org
Subject: Re: How git affects kernel.org performance
Date: Mon, 8 Jan 2007 18:18:12 -0800 [thread overview]
Message-ID: <20070109021812.GE44262@sgi.com> (raw)
In-Reply-To: <20070108170934.dafc5b81.pj@sgi.com>
On Mon, Jan 08, 2007 at 05:09:34PM -0800, Paul Jackson wrote:
> Jeff wrote:
> > Something I just thought of: ATA and SCSI hard disks do their own
> > read-ahead.
>
> Probably this is wishful thinking on my part, but I would have hoped
> that most of the read-ahead they did was for stuff that happened to be
> on the cylinder they were reading anyway. So long as their read-ahead
> doesn't cause much extra or delayed disk head motion, what does it
> matter?
And they usually won't readahead if there is another command to
process, though they can be set up to read unrequested data in
spite of outstanding commands.
When they are reading ahead, they'll only fetch LBAs beyond the last
request until a buffer fills or the readahead gets interrupted.
jeremy
next prev parent reply other threads:[~2007-01-09 2:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20061216094421.416a271e.randy.dunlap@oracle.com>
[not found] ` <20061216095702.3e6f1d1f.akpm@osdl.org>
[not found] ` <458434B0.4090506@oracle.com>
[not found] ` <1166297434.26330.34.camel@localhost.localdomain>
[not found] ` <1166304080.13548.8.camel@nigel.suspend2.net>
[not found] ` <459152B1.9040106@zytor.com>
[not found] ` <1168140954.2153.1.camel@nigel.suspend2.net>
[not found] ` <45A08269.4050504@zytor.com>
[not found] ` <45A083F2.5000000@zytor.com>
[not found] ` <Pine.LNX.4.64.0701062130260.3661@woody.osdl.org>
[not found] ` <20070107085526.GR24090@1wt.eu>
2007-01-07 9:15 ` How git affects kernel.org performance Andrew Morton
2007-01-07 9:38 ` Rene Herman
2007-01-08 3:05 ` Suparna Bhattacharya
2007-01-08 12:58 ` Theodore Tso
2007-01-08 13:41 ` Johannes Stezenbach
2007-01-08 13:56 ` Theodore Tso
2007-01-08 13:59 ` Pavel Machek
2007-01-08 14:17 ` Theodore Tso
2007-01-08 13:43 ` Jeff Garzik
2007-01-09 1:09 ` Paul Jackson
2007-01-09 2:18 ` Jeremy Higdon [this message]
[not found] ` <20070109075945.GA8799@mail.ustc.edu.cn>
2007-01-09 7:59 ` Fengguang Wu
2007-01-09 16:23 ` Linus Torvalds
[not found] ` <20070110015739.GA26978@mail.ustc.edu.cn>
2007-01-10 1:57 ` Fengguang Wu
2007-01-10 1:57 ` Fengguang Wu
2007-01-10 1:57 ` Fengguang Wu
2007-01-10 3:20 ` Nigel Cunningham
[not found] ` <20070110140730.GA986@mail.ustc.edu.cn>
2007-01-10 14:07 ` Fengguang Wu
2007-01-10 14:07 ` Fengguang Wu
2007-01-10 14:07 ` Fengguang Wu
2007-01-12 10:54 ` Nigel Cunningham
2007-01-09 7:59 ` Fengguang Wu
2007-01-09 7:59 ` Fengguang Wu
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