Re: [git patches] IDE update

Ondrej Zary
2005-07-05T10:25:40Z

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