From: Markus Roeffen (markus.roeffen_at_iws.uni-stuttgart.de)
Date: Tue Apr 10 2007 - 09:11:23 CEST
Message-ID: <461B389B.1080109@iws.uni-stuttgart.de> Date: Tue, 10 Apr 2007 09:11:23 +0200 From: Markus Roeffen <markus.roeffen@iws.uni-stuttgart.de> Subject: Re: Antw: Re: [suse-sles-e] Re: catastrophic disk-performance on SLES10 with SATA drives
Hallo Andreas,
the scheduler-paramter "nr_requests" in my SLES10 was set to 128.
According to some performance guides on the internet, setting this
parameter to 1024 should improve the IO performance.
You can view your parameter settings with:
cat /sys/block/<your device>/queue/nr_requests
And you can set the parameter with:
echo "1024" > /sys/block/<your device>/queue/nr_requests
For further instructions (with some benchmarks) can be found (and should
be read before editing any parameter) at:
http://nextre.it/oracledocs/ioscheduler_01.html
Maybe this can help you. If the new setting works for you, please let me
know.
Best regards
Markus
Markus Roeffen wrote:
> Hello Andreas,
>
> I have already played around with this settings in March, but it
> didn't work.
>
> (By the way: You can check your scheduler with the following command:
> cat /var/log/boot.msg|grep -i "scheduler" )
>
> But I still have my bookmarks from these trial & error sessions, so
> maybe I can give you some interesting links.
>
> http://www-941.ibm.com/collaboration/wiki/display/LinuxP/Performance+Tuning
>
>
> http://download.boulder.ibm.com/ibmdl/pub/software/dw/linux390/perf/pht_share_tampa_2007.pdf
>
>
> http://drwetter.org/suse10.1/report.suse-10.1.html
>
> I think, I've also written some other links on paper, but these are
> partially in German.
>
> Best regards
> Markus
>
>> Hi Markus,
>>
>> just one comment for today.
>> I've never tested it, but I can imagine that the elevator mode could
>> have an impact. SuSE comes with elevator=cfg as standard. In this mode
>> the kernel tries to reorder write requests. This could be
>> counterproductive
>> if you have a hardware raid with buffer memory and own logic of
>> summing up
>> write/read requests.
>>
>> I found http://www.redhat.com/magazine/008jun05/features/schedulers/
>> to be really interesting.
>>
>> Probably you have time and fun trying it.
>>
>> Best regards
>> Andreas Mock
>
-- ------------------------------- Markus Roeffen Institut für Wasserbau IWS Universität Stuttgart Pfaffenwaldring 61 70569 Stuttgart Tel: +49(0)711/685-67010 Fax: +49(0)711/685-67020 Mail: markus.roeffen@iws.uni-stuttgart.de --------------------------------------------------------------------- To unsubscribe, e-mail: suse-sles-e-unsubscribe@suse.com For additional commands, e-mail: suse-sles-e-help@suse.com
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