From: Joel Becker <jlbec@evilplan.org>
To: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: Jeff Garzik <jgarzik@mandrakesoft.com>,
Andrew Morton <akpm@zip.com.au>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: fadvise syscall?
Date: Sun, 17 Mar 2002 19:20:28 +0000 [thread overview]
Message-ID: <20020317192028.U4836@parcelfarce.linux.theplanet.co.uk> (raw)
In-Reply-To: <3C945635.4050101@mandrakesoft.com> <3C945A5A.9673053F@zip.com.au> <3C945D7D.8040703@mandrakesoft.com> <5.1.0.14.2.20020317131910.0522b490@pop.cus.cam.ac.uk>
In-Reply-To: <5.1.0.14.2.20020317131910.0522b490@pop.cus.cam.ac.uk>; from aia21@cam.ac.uk on Sun, Mar 17, 2002 at 01:41:37PM +0000
On Sun, Mar 17, 2002 at 01:41:37PM +0000, Anton Altaparmakov wrote:
> When you want large data streaming, i.e. you start getting worried about
> memory pressure, then you want open(2) + O_DIRECT. No caching done. Perfect
> for large data streams and we have that already. I agree that you may want
> some form of asynchronous read ahead with passed pages being dropped from
> the cache but that could be just a open(2) + O_SEQUENTIAL (doesn't exist yet).
O_DIRECT isn't the right thing for large streaming. You want
readahead and dropbehind. O_DIRECT takes substantial penalties for its
lack of copy/cacheing. This works fine in certain circumstances
(applications that keep their own caching), but for something like a
video or mp3, you'll win with working dropbehind easily.
Joel
--
Life's Little Instruction Book #444
"Never underestimate the power of a kind word or deed."
http://www.jlbec.org/
jlbec@evilplan.org
next prev parent reply other threads:[~2002-03-17 19:20 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-17 8:39 fadvise syscall? Jeff Garzik
2002-03-17 8:56 ` Andrew Morton
2002-03-17 9:10 ` Jeff Garzik
2002-03-17 20:18 ` Richard Gooch
2002-03-17 13:41 ` Anton Altaparmakov
2002-03-17 14:31 ` Simon Richter
2002-03-17 14:56 ` Jan Hudec
2002-03-17 15:00 ` Anton Altaparmakov
2002-03-17 19:20 ` Joel Becker [this message]
2002-03-17 23:59 ` Anton Altaparmakov
2002-03-18 7:28 ` Jeff Garzik
2002-03-18 7:55 ` Andrew Morton
2002-03-18 8:07 ` Jeff Garzik
2002-03-18 8:17 ` Andrew Morton
2002-03-18 16:41 ` Richard Gooch
2002-03-18 19:00 ` Andrew Morton
2002-03-18 19:15 ` Richard Gooch
2002-03-22 16:05 ` Pavel Machek
2002-03-24 6:38 ` Stevie O
2002-03-24 11:24 ` Pavel Machek
2002-03-24 12:52 ` Anton Altaparmakov
2002-03-25 11:12 ` Pavel Machek
2002-03-18 8:05 ` Joel Becker
2002-03-18 8:10 ` Jeff Garzik
2002-03-18 8:20 ` Joel Becker
2002-03-18 8:14 ` Andrew Morton
2002-03-18 14:39 ` Martin K. Petersen
2002-03-18 19:15 ` Andrew Morton
2002-03-18 19:42 ` Martin K. Petersen
2002-03-19 20:08 ` Eric W. Biederman
2002-03-19 23:38 ` Martin K. Petersen
2002-03-17 15:13 ` Ken Hirsch
2002-03-17 17:14 ` Anton Altaparmakov
2002-03-17 18:31 ` Mark Mielke
2002-03-17 18:35 ` Ken Hirsch
2002-03-17 19:06 ` Anton Altaparmakov
2002-03-17 20:19 ` Ken Hirsch
2002-03-18 0:12 ` Anton Altaparmakov
[not found] ` <a73ujs$5mc$1@cesium.transmeta.com>
2002-03-18 8:58 ` Jan Hudec
2002-03-18 10:08 ` Jeff Garzik
2002-03-18 17:29 ` Mark Mielke
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