Re: poor sata performance on 2.6

Denis Vlasenko
2004-04-15T17:33:11Z

On Thursday 15 April 2004 17:48, Konstantin Sobolev wrote:
> On Thursday 15 April 2004 18:33, Justin Cormack wrote:
> > On Thu, 2004-04-15 at 15:26, Konstantin Sobolev wrote:
> > > On Thursday 15 April 2004 18:00, Justin Cormack wrote:
> > > > hmm, odd. I get 50MB/s or so from normal (7200, 8MB cache) WD disks,
> > > > and Seagate from the same controller. Can you send lspci,
> > > > /proc/interrupts and dmesg...
> > >
> > > Attached are files for 2.6.5-mm5 with highmem, ACPI and APIC turned
> > > off.
> >
> > ah. Make a filesystem on it and mount it and try again. I see you have
> > no partition table and so probably no filesystem. This means the block
> > size is set to default 512byte not 4k which makes disk operations slow.
> > Any filesystem should default to block size of 4k, eg ext2.
>
> Very interesting!
> created partition table,
> kos sata # mkfs.ext2 /dev/sda1
> [..skipped..]
> kos mnt # cd /
> kos / # mkdir wd
> kos / # mount /dev/sda1 /wd
> kos / # hdparm -t -a8192 /dev/sda
>
> /dev/sda:
> setting fs readahead to 8192
> readahead = 8192 (on)
> Timing buffered disk reads: 82 MB in 3.03 seconds = 27.02 MB/sec
>
> kos / # mount | grep sda
> /dev/sda1 on /wd type ext2 (rw)
> kos / # hdparm -t -a8192 /dev/sda
>
> /dev/sda:
> setting fs readahead to 8192
> readahead = 8192 (on)
> Timing buffered disk reads: 206 MB in 3.02 seconds = 68.15 MB/sec
> kos / # hdparm -t -a8192 /dev/sda
>
> /dev/sda:
> setting fs readahead to 8192
> readahead = 8192 (on)
> Timing buffered disk reads: 206 MB in 3.02 seconds = 68.18 MB/sec
>
> So first time it gave the same loosy 27 MB/s and subsequent tests give
> pretty good 68 MB/s! Why?

Time to CC ide/libata/block layer folks

Jeff Garzik <jgarzik@pobox.com>
libata man

IDE DRIVER [GENERAL]
P: Bartlomiej Zolnierkiewicz
M: B.Zolnierkiewicz@elka.pw.edu.pl
L: linux-kernel@vger.kernel.org
L: linux-ide@vger.kernel.org
S: Maintained

BLOCK LAYER
P: Jens Axboe
M: axboe@suse.de
L: linux-kernel@vger.kernel.org
S: Maintained

SIS 5513 IDE CONTROLLER DRIVER
P: Lionel Bouton
M: Lionel.Bouton@inet6.fr
W: http://inet6.dyn.dhs.org/sponsoring/sis5513/index.html
W: http://gyver.homeip.net/sis5513/index.html
S: Maintained

--
vda