Re: [git patches] IDE update

[Jens Axboe <axboe@suse.de>]

On Tue, Jul 05 2005, Ondrej Zary wrote:
> 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

Can you post full dmesg of 2.4 and 2.6 kernel boot? What does hdparm
-I/-i say for both kernels?

-- 
Jens Axboe