Re: [git patches] IDE update

[Ondrej Zary <linux@rainbow-software.org>]

Jens Axboe wrote:
> On Tue, Jul 05 2005, Ondrej Zary wrote:
>
> > André Tomt wrote:
> >
> > > Al Boldi wrote:
> > >
> > >
> > > > Bartlomiej Zolnierkiewicz wrote: {
> > > >
> > > >
> > > > > > > On 7/4/05, Al Boldi <a1426z@gawab.com> wrote:
> > > > > > > Hdparm -tT gives 38mb/s in 2.4.31
> > > > > > > Cat /dev/hda > /dev/null gives 2% user 33% sys 65% idle
> > > > > > >
> > > > > > > Hdparm -tT gives 28mb/s in 2.6.12
> > > > > > > Cat /dev/hda > /dev/null gives 2% user 25% sys 0% idle 73% IOWAIT
> > >
> > >
> > > The "hdparm doesn't get as high scores as in 2.4" is a old discussed to 
> > > death "problem" on LKML. So far nobody has been able to show it affects 
> > > anything  but that pretty useless quasi-benchmark.
> >
> > No, it's not a problem with hdparm. hdparm only shows that there is 
> > _really_ a problem:
> >
> > 2.6.12
> > root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=512
> > count=1048576
> > 1048576+0 records in
> > 1048576+0 records out
> >
> > real    0m32.339s
> > user    0m1.500s
> > sys     0m14.560s
> >
> > 2.4.26
> > root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=512
> > count=1048576
> > 1048576+0 records in
> > 1048576+0 records out
> >
> > real    0m23.858s
> > user    0m1.750s
> > sys     0m15.180s
>
>
> Perhaps some read-ahead bug. What happens if you use bs=128k for
> instance?
Nothing - it's still the same.

root@pentium:/home/rainbow# time dd if=/dev/hda of=/dev/null bs=128k 
count=4096
4096+0 records in
4096+0 records out

real    0m32.832s
user    0m0.040s
sys     0m15.670s

--
Ondrej Zary
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