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
--
Ondrej Zary
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