Jens Axboe wrote:
> 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?
> 

The 2.4.26 kernel is the one from Slackware 10.0 bootable install CD.
dmesg outputs attached, hdparm -i and hdparm -I shows the same in both
kernels (compared using diff) - attached too.

-- 
Ondrej Zary