Linux disk performance slower than Freebsd. Advise needed.

Linux disk performance slower than Freebsd. Advise needed.

Post by qaza » Sat, 31 Aug 2002 18:22:43



Hi,

I done a disk benchmark. And i found that:
Linux 7.2 (SMP, ext3) disk IO performance is 18% slower than Freebsd (SMP, ufs).
Both are using same SCSI 80.000MB/s transfers.

Is it the sync/async cause, flock(), journaling, ext3 filesystem..?

Any way to increase/tuning the disk performance on linux.

Help and advise needed.
Thanks.

-Qaz

 
 
 

Linux disk performance slower than Freebsd. Advise needed.

Post by Bernd Eckenfel » Sat, 31 Aug 2002 18:58:58



Quote:> I done a disk benchmark. And i found that:
...
> Is it the sync/async cause, flock(), journaling, ext3 filesystem..?

depends on the disk benachmark you have used, but could be anything. the
most common config problems may be driver tuning (dma modes and stuff) and
journaling levels (eg data-journal is for most operations quite slow but
reliable).

Greetings
Bernd

 
 
 

Linux disk performance slower than Freebsd. Advise needed.

Post by Karl Heye » Sun, 01 Sep 2002 00:46:45



> Hi,

> I done a disk benchmark. And i found that:
> Linux 7.2 (SMP, ext3) disk IO performance is 18% slower than Freebsd (SMP, ufs).
> Both are using same SCSI 80.000MB/s transfers.

> Is it the sync/async cause, flock(), journaling, ext3 filesystem..?

> Any way to increase/tuning the disk performance on linux.

IIRC ext3 is fully optimised yet so there are weaks points with the
fileystem is certain cases.  Check against ext2 but you have to take
into consideration the performance/reliability trade-off

RH7.2 is is probably using a slightly older kernel as well.

karl.

 
 
 

Linux disk performance slower than Freebsd. Advise needed.

Post by mjt » Sun, 01 Sep 2002 01:24:03


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> I done a disk benchmark.

... which benchmark?   you may be comparing apples to oranges.

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Michael J. Tobler: motorcyclist, surfer,  #    Black holes result
 skydiver, and author: "Inside Linux",     #   when God divides the  
 "C++ HowTo", "C++ Unleashed"              #     universe by zero

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1. Bad network/disk/IO performance of Linux compared to FreeBSD

From a letter in private Email sent to me:

2.0.30, but I was testing more than just network performance alone.  I
wanted to see if Linux would drop packets on a PPP interface while the
disk was very busy.  Not only did it drop packets, it stopped
servicing the serial interrupt entirely until the copy from CD to disk
ended.  I followed the recommendations about unmasking the disk
interrupt and using IRQtune to put the serial interrupt at a higher
priority than the disk interrupt, but that did not help.

The same test on the same hardware using FreeBSD ran flawlessly -- no
dropped packets at all.

--
David Kastrup                                     Phone: +49-234-700-5570

Institut fr Neuroinformatik, Universit?tsstr. 150, 44780 Bochum, Germany

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