From: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
To: Andrew Morton <akpm@osdl.org>
Cc: "Måns Rullgård" <mru@users.sourceforge.net>,
linux-kernel@vger.kernel.org
Subject: Re: Disk performance degradation
Date: Fri, 1 Aug 2003 00:17:31 +0200 (MET DST) [thread overview]
Message-ID: <Pine.SOL.4.30.0307312351500.6434-100000@mion.elka.pw.edu.pl> (raw)
In-Reply-To: <20030731141517.0ceccc77.akpm@osdl.org>
On Thu, 31 Jul 2003, Andrew Morton wrote:
> mru@users.sourceforge.net (Mĺns Rullgĺrd) wrote:
> >
> > Mike Dresser <mdresser_l@windsormachine.com> writes:
> >
> > > Probably for reasons like that. For some reason, I can't set my ICH4
> > > based controller(ASUS P4B533) and Quantum Fireball AS40.0 to more than
> > > 255. Kernel is 2.4.21
> >
> > It appears that in 2.[56] kernels the unit for readahead is bytes,
> > rather than sectors, as used in 2.4 kernels.
>
> The ioctl which is used by
>
> blockdev --setra
>
> is still in 512-byte units.
>
> There are other backdoors such as IDE-private /proc files which can be used
> to set readahead. I'm not sure what units they use, and I don't know what
> mechanism hdparm is using to diddle readahead.
in 2.4.x:
/proc/ide/hdX/settings
breada_readahead - BLKRA{GET/SET}
file_readahead - BLKFRA{GET/SET}
both are in 1024 bytes units
in 2.6.x they are gone :-).
and hdparm is using BLKRA{GET/SET}
--
Bartlomiej
next prev parent reply other threads:[~2003-07-31 22:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-29 16:21 Disk performance degradation Voluspa
2003-07-29 16:50 ` Lou Langholtz
2003-07-30 4:17 ` Voicu Liviu
2003-07-30 21:02 ` Mike Dresser
2003-07-31 8:35 ` Måns Rullgård
2003-07-31 14:00 ` Mike Dresser
2003-07-31 21:15 ` Andrew Morton
2003-07-31 22:17 ` Bartlomiej Zolnierkiewicz [this message]
2003-07-30 8:50 ` Stefano Rivoir
2003-07-30 10:55 ` Andrew Morton
2003-07-30 16:06 ` Stefano Rivoir
2003-07-30 18:44 ` Andrew Morton
2003-07-31 0:21 ` Rahul Karnik
2003-07-31 6:59 ` Stefano Rivoir
2003-07-31 7:16 ` Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2003-07-30 11:43 Frederick, Fabian
2003-07-29 12:00 Stefano Rivoir
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