read from cache is much slower with feisty than all previous ubuntu versions

[nigra]

Here is the result of the hdparm test on my laptop (Toshiba M40x-119)

/dev/sda:
 Timing cached reads: 1226 MB in 2.00 seconds = 612.38 MB/sec
 Timing buffered disk reads: 84 MB in 3.05 seconds = 27.54 MB/sec

Buffered disk access is the same, no problem. But cached reads were
~1500 MB/sec on my laptop with breezy,dapper,edgy. The system is slow especially
slow for example when building a dvd iso for backup, which I never experienced
with the previous versions of ubuntu.
Exactly the same problem is mentioned
Here: http://ubuntuforums.org/showthread.php?t=366723&highlight=feisty+hdparm
And here: http://ubuntuforums.org/showthread.php?t=356627&highlight=feisty+hdparm

Running Feisty Fawn Herd5 up-to-date

[Chris Rose (chris-vault5)]

Thanks for taking the time to report this bug. Unfortunately we can't fix it, because your description doesn't yet have enough information.

Please include the following additional information, if you have not already done so (please pay attention to lspci's additional options), as required by the Ubuntu Kernel Team:
1. Please include the output of the command "uname -a" in your next response. It should be one, long line of text which includes the exact kernel version you're running, as well as the CPU architecture.
2. Please run the command "dmesg > dmesg.log" and attach the resulting file "dmesg.log" to this bug report.
3. Please run the command "lspci -vvnn > lspci-vvnn.log" and attach the resulting file "lspci-vvnn.log" to this bug report.

For your reference, the full description of procedures for kernel-related bug reports is available at [WWW] http://wiki.ubuntu.com/DebuggingKernelProblems . Thanks in advance!

[nigra (guneyvolkan-gmail)]

unname -a:
Linux julien-laptop 2.6.20-9-generic #2 SMP Mon Feb 26 03:01:44 UTC 2007 i686 GNU/Linux

   If it is useful, the results don't change with other kernels such as lowlatency kernel
from the universe or the kernel I've compiled from the repos.

[Chris Rose (chris-vault5)]

Thank you.

[Frank (frank-schaeffer)]

Here too, on a Thinkpad Z61m, Feisty Fawn Herd5, actually updated

uname -a:
Linux Newton 2.6.20-9-generic #2 SMP Mon Feb 26 03:01:44 UTC 2007 i686 GNU/Linux

[Frank (frank-schaeffer)]

And here dmesg.log
Similar, along with a Desktop-PC and SATAII-Harddisk
Best regards

Frank

[Conn O Griofa (psyke83)]

Hi,

I'm suffering the same bug on my systems. I'm providing logs from my laptop, a Dell Inspiron 510m. Prior to Feisty, cached reads approached 1500MB/s. Using kernel version 2.6.20-9-generic, everything up-to-date.

conn@inspiron:~/slowcache$ uname -a
Linux inspiron 2.6.20-9-generic #2 SMP Mon Feb 26 03:01:44 UTC 2007 i686 GNU/Linux

conn@inspiron:~/slowcache$ sudo hdparm -Tt /dev/hda
/dev/hda:
 Timing cached reads: 1046 MB in 2.00 seconds = 522.33 MB/sec
 Timing buffered disk reads: 80 MB in 3.09 seconds = 25.85 MB/sec

[VF (vfiend)]

Same problem here, let me know if you need more logs from me in addition to what's already been posted here.

[Kyle McMartin (kyle)]

Can you reproduce with http://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.20.2.tar.gz upstream 2.6.20.2?

[nigra (guneyvolkan-gmail)]

  Kyle,
  Sorry for late answer, I am afraid I switched back to edgy few days ago, so I cannot test with the new kernel. But I installed feisty kernel(both the generic one and the one I compiled by customizing it) in edgy. The problem does not occur with the same kernel in edgy, cached reads are normal (~1500 MB/S). I don't know if this info will be any useful to lead your work in some direction but just wanted to let you know with that hope.
  It would be great if the other folks had tried that if they still hold feisty on their workstations. Thanks.

[Mário Vrablanský (vrablansky)]

Hi

The same problem for me

mario@notebook:~$ sudo hdparm -tT /dev/hda
Password:

/dev/hda:
 Timing cached reads: 992 MB in 2.00 seconds = 495.64 MB/sec
 Timing buffered disk reads: 96 MB in 3.01 seconds = 31.85 MB/sec
mario@notebook:~$ hdparm -i /dev/hda
/dev/hda: Permission denied
mario@notebook:~$ sudo hdparm -i /dev/hda

In edgy i had more than 1000 MB/sec . I`ve attached some logs .I use newest kernel

mario@notebook:~$ uname -a
Linux notebook 2.6.20-10-generic #2 SMP Mon Mar 12 00:02:49 UTC 2007 i686 GNU/Linux

Will check also kernel 386

[Mário Vrablanský (vrablansky)]

Please ignore my last dmesg log it`s from different machine :(
Thanks

[Ben Collins (ben-collins)]

nigra's comments seem to suggest that the kernel was operating normally for him (under edgy userspace), so likely not a kernel issue.

[VF (vfiend)]

Re-opening given the duplicate, changing so that it's not assigned to any package

[A. W. Moore (angelyn147)]

Me too.

On Feisty:
/dev/sda:
 Timing cached reads: 1242 MB in 2.00 seconds = 619.52 MB/sec
 Timing buffered disk reads: 222 MB in 3.02 seconds = 73.45 MB/sec

I booted Gutsy tribe 4 today and got very similar numbers.

If I boot Edgy or Knoppix 5.01, cached read performance is very
close to doubled (about 1200 MB/sec).

Logs attached are from Feisty:
% uname -a
Linux ni 2.6.20-15-generic #2 SMP Sun Apr 15 07:36:31 UTC 2007 i686 GNU/Linux

I am willing to provide logs from Gutsy or Edgy or perform tests
under them, insofar as I'm able. Actions like grepping through a large
directory are very slow, so I'm interested in any solution. Was really
hoping Gutsy would just solve it. :(

[Adam Niedling (krychek)]

Feisty is not supported anymore. Please retest this issue with a later version of Ubuntu and reopen this report.