[27183] in Athena Bugs
Re: linux 9.4.46: kernel
daemon@ATHENA.MIT.EDU (William Cattey)
Thu Feb 14 20:00:14 2008
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From: William Cattey <wdc@mit.edu>
Date: Thu, 14 Feb 2008 19:59:50 -0500
To: Ken T Takusagawa <kenta@mit.edu>
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Someone else may choose to chime in on this issue, but I would make a
couple of points:
Athena 9.4.46 is running the 2.6.9 kernel because it is RHEL 4 based.
Whereas Debian Etch, as you report, is running 2.6.18.
Running your tests on a Dell Optiplex 745 running RHEL 5 which has a
2.6.18 kernel gives:
$ time dd if=/dev/zero of=/tmp.test bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 5.4553 seconds, 197 MB/s
0.000u 1.818s 0:05.45 33.2% 0+0k 0+0io 0pf+0w
$ sudo /sbin/hdparm -Tt /dev/sda:
Timing cached reads: 12268 MB in 2.00 seconds = 6142.45 MB/sec
Timing buffered disk reads: 176 MB in 3.02 seconds = 58.36 MB/sec
And these numbers are a little closer to what you're getting on Etch.
Soooo... The remedy is to upgrade the kernel. Athena 10 based on
Ubuntu with a 2.6.20 or later kernel is currently under development.
Thanks for taking the time to ask about how performance might be
improved.
-Bill
----
William Cattey
Linux Platform Coordinator
MIT Information Services & Technology
N42-040M, 617-253-0140, wdc@mit.edu
http://web.mit.edu/wdc/www/
On Feb 12, 2008, at 11:17 PM, Ken T Takusagawa wrote:
> System name: m37-332-8.mit.edu
> Type and version: i686 9.4.46
> Display type: ATI Technologies Inc RV516 [Radeon X1300/X1550 Series]
>
> Shell: /bin/athena/bash
> Window manager: sawfish
>
> What were you trying to do?
> Run programs which are hard disk intensive (local hard disk)
>
> What's wrong:
> Athena Linux (in particular on the new Dell Optiplex 745)
> has horrible hard drive performance. For example:
>
> $ time dd if=/dev/zero of=/tmp/test bs=1M count=1024
> 1024+0 records in
> 1024+0 records out
>
> real 1m34.918s
> user 0m0.001s
> sys 0m5.738s
>
> # hdparm -tT /dev/hda
>
> /dev/hda:
> Timing cached reads: 4220 MB in 2.00 seconds = 2110.32
> MB/sec
> Timing buffered disk reads: 12 MB in 3.20 seconds =
> 3.76 MB/sec
>
> I installed Debian Etch (i686, ext3 Filesystem, kernel 2.6.18-6-686)
> on the same hardware and got:
>
> $ time dd if=/dev/zero of=/tmp/test bs=1M count=1024
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes (1.1 GB) copied, 4.04747 seconds, 265 MB/s
>
> real 0m4.074s
> user 0m0.000s
> sys 0m2.012s
>
>
> $ sudo hdparm -tT /dev/sda
>
> /dev/sda:
> Timing cached reads: 6680 MB in 2.00 seconds = 3342.88
> MB/sec
> Timing buffered disk reads: 242 MB in 3.03 seconds =
> 79.95 MB/sec
>
> I was able to replicate these results on two machines. There is a
> 23x speed difference in the "dd" test, and 21x difference in the
> "buffered disk reads" hdparm test.
>
> What should have happened:
>
> Please describe any relevant documentation references:
> See also /mit/sipbzlog/sbi/athena on the conversation starting on
> Tue Feb 12 22:20:54 2008
