Ubuntu
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Bug #337419
Comment #1

Comment 1 for bug 337419

Revision history for this message

MikeM (michaelm) wrote on 2009-10-23:

Hi,

I have seen this too using custom kernels on Hardy and on the current RC of Karmic Koala. The performance regression I have seen using the standard Linux CCISS kernel driver is a drop of about 66% performance. The performance regression was introduced in 2.6.29-rc1 and is in current kernels up to and including 2.6.32-rc5. Since Karmic Koala is based on 2.6.31 is shares the same performance drop when compared with Hardy.

Since Ihave seen mention of Canonical trying to get Ubuntu certified on HP kit, I would expect there to be a vested interest for both Canonical and HP to resolve this problem.

I have put detailed performance tests at the following URL to highlight this issue.
http://bugzilla.kernel.org/show_bug.cgi?id=13127

In summary using the standard Hardy kernel (2.6.24-24-server) and custom kernels (using the kernel config from 2.6.24-24-server to keep the same options) listed below I see around 90MB/s while reading off a single SAS 146GB 10k RPM drive in a RAID-0 logical drive on a DL360G5 and DL380G5. From 2.6.29-rc1 through to current kernels I see around 34MB/s while doing the same test.

The following give around 90MB/s read of the logical drive:
2.6.24-24-server
26.24.7
2.6.25.20
2.6.26.8
2.6.27.37
2.6.28.10

The following give around 34MB/s read of the same logical drive:
2.6.29-rc1
2.6.29
2.6.29.1 through 2.6.29.6
2.6.30.9
2.6.31.4
2.6.32-rc5

The test I performed on all the above was a simple:
dd if=/dev/cciss/c0d1 of=/dev/null bs=1024k count=1024
dd if=/dev/cciss/c0d1 of=/dev/null bs=1024k count=2048

Performance from Hardy:
--------------------------
Wed Oct 21 16:40:54 BST 2009
Linux uk-ditnas902 2.6.24-24-server #1 SMP Fri Sep 18 16:47:05 UTC 2009 x86_64
GNU/Linux
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 11.83 s, 90.8 MB/s
2048+0 records in
2048+0 records out
2147483648 bytes (2.1 GB) copied, 23.6072 s, 91.0 MB/s
--------------------------

Performance from current Karmic Koala:
---------------------
Linux uk-ditnas903 2.6.31-14-server #48-Ubuntu SMP Fri Oct 16 15:07:34 UTC 2009 x86_64 GNU/Linux
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 31.0771 s, 34.6 MB/s
------
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 31.1101 s, 34.5 MB/s
---------------------

Hi,

I have seen this too using custom kernels on Hardy and on the current RC of Karmic Koala. The performance regression I have seen using the standard Linux CCISS kernel driver is a drop of about 66% performance. The performance regression was introduced in 2.6.29-rc1 and is in current kernels up to and including 2.6.32-rc5.  Since Karmic Koala is based on 2.6.31 is shares the same performance drop when compared with Hardy.