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Message-ID: <42CA5EAD.7070005@rainbow-software.org>
Date: Tue, 05 Jul 2005 12:19:25 +0200
From: Ondrej Zary <linux@rainbow-software.org>
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To: Jens Axboe <axboe@suse.de>
CC: "=?ISO-8859-1?Q?Andr=E9_Tomt?=" <andre@tomt.net>,
       Al Boldi <a1426z@gawab.com>,
       "'Bartlomiej Zolnierkiewicz'" <bzolnier@gmail.com>,
       "'Linus Torvalds'" <torvalds@osdl.org>, linux-ide@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [git patches] IDE update
References: <200507042033.XAA19724@raad.intranet> <42C9C56D.7040701@tomt.net> <42CA5A84.1060005@rainbow-software.org> <20050705101414.GB18504@suse.de>
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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