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 <[email protected]> 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
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