[kernel disk scheduler] tasks that use disk heavily starve other tasks of disk access

[N7DR]

There are several ways to demonstrate this problem. This is an easy one:

1. On a disk with lots of space, create a large file X of size ~8GB
2. Issue the command "split -b 4000m X"

This will keep the disk occupied nicely. Until the job finishes, even a dual-core machine will respond erratically. Some jobs will be fine, while others will freeze for long periods of time. I believe that the difference between freezing and non-freezing jobs is that the jobs that are freezing are being greatly starved of even small amounts of time needed to perform disk accesses.

I experience this issue on 64-bit gutsy on a dual-core system with a 500GB drive that is about 50% full.

[Jean-Baptiste Lallement (jibel)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in it recently. We were wondering is this still an issue for you? Can you try with latest Ubuntu release? Thanks in advance.

[N7DR (doc-evans)]

Yup; I ran the test as described, and this is still an issue on an up-to-date hardy amd64 Kubuntu system.

[Jean-Baptiste Lallement (jibel)]

Please include the following additional information, if you have not already done so (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" after a fresh boot and attach the resulting file "dmesg.log" to this bug report.
3. Please run the command "sudo lspci -vvnn > lspci-vvnn.log" and attach the resulting file "lspci-vvnn.log" to this bug report.
4. Can you run your test and attach the file /var/log/kern.log

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

[Leann Ogasawara (leannogasawara)]

The Ubuntu Kernel Team is planning to move to the 2.6.27 kernel for the upcoming Intrepid Ibex 8.10 release. As a result, the kernel team would appreciate it if you could please test this newer 2.6.27 Ubuntu kernel. There are one of two ways you should be able to test:

1) If you are comfortable installing packages on your own, the linux-image-2.6.27-* package is currently available for you to install and test.

--or--

2) The upcoming Alpha5 for Intrepid Ibex 8.10 will contain this newer 2.6.27 Ubuntu kernel. Alpha5 is set to be released Thursday Sept 4. Please watch http://www.ubuntu.com/testing for Alpha5 to be announced. You should then be able to test via a LiveCD.

Please let us know immediately if this newer 2.6.27 kernel resolves the bug reported here or if the issue remains. More importantly, please open a new bug report for each new bug/regression introduced by the 2.6.27 kernel and tag the bug report with 'linux-2.6.27'. Also, please specifically note if the issue does or does not appear in the 2.6.26 kernel. Thanks again, we really appreicate your help and feedback.

[Jean-Baptiste Lallement (jibel)]

We are closing this bug report because it lacks the information we need to investigate the problem, as described in the previous comments. Please reopen it if you can give us the missing information, and don't hesitate to submit bug reports in the future. To reopen the bug report you can click on the current status, under the Status column, and change the Status back to "New". Thanks again!

[N7DR (doc-evans)]

Please reopen this bug.

Exactly the same behaviour occurs with intrepid. Even on completely different hardware. (In fact, it seems to happen on every system I've tried it on, so it seems like it should be easy for developers to duplicate.)

Here are the files you requested:

1. uname -a:
  Linux homebrew 2.6.27-8-generic #1 SMP Thu Nov 6 17:38:14 UTC 2008 x86_64 GNU/Linux

2. dmesg.log:
  attached
3. sudo lspci -vvnn > lspci-vvnn.log
  will attach in additional report (it doesn't seem that one can attach more than one file to a comment)

4. kern.log
  Nothing was written to the file when I ran the test.
  Here is the file, though.

Nov 20 11:14:14 homebrew kernel: [12798.123651] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input6
Nov 20 11:28:47 homebrew kernel: [13671.837453] npviewer.bin[7737]: segfault at ff9d1e4c ip 00000000ff9d1e4c sp 00000000fff9fa7c error 14
Nov 20 12:31:46 homebrew kernel: [17450.633674] CIFS: Unknown mount option bg
Nov 20 12:31:52 homebrew kernel: [17456.640080] CIFS VFS: Error connecting to IPv4 socket. Aborting operation
Nov 20 12:31:52 homebrew kernel: [17456.640091] CIFS VFS: cifs_mount failed w/return code = -113
Nov 20 21:49:57 homebrew kernel: [50941.746094] npviewer.bin[24454]: segfault at 26743d6d ip 00000000f6915b25 sp 00000000ff94ddc0 error 4 in libflashplayer.so[f68cf000+951000]
Nov 21 08:19:14 homebrew kernel: [88698.477549] type=1505 audit(1227280754.451:4): operation="profile_replace" name="/usr/lib/cups/backend/cups-pdf" name2="default" pid=4478
Nov 21 08:19:14 homebrew kernel: [88698.479080] type=1505 audit(1227280754.451:5): operation="profile_replace" name="/usr/sbin/cupsd" name2="default" pid=4478
Nov 21 10:41:11 homebrew kernel: [97215.467152] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input7
Nov 21 13:57:32 homebrew kernel: [108996.216516] usb 3-1: new full speed USB device using uhci_hcd and address 2
Nov 21 13:57:32 homebrew kernel: [108996.436378] usb 3-1: configuration #1 chosen from 1 choice
Nov 21 14:12:55 homebrew kernel: [109919.085051] cdrom: This disc doesn't have any tracks I recognize!
Nov 21 14:12:55 homebrew kernel: [109919.103768] end_request: I/O error, dev sr1, sector 0
Nov 21 14:12:55 homebrew kernel: [109919.103777] Buffer I/O error on device sr1, logical block 0
Nov 21 14:12:55 homebrew kernel: [109919.110550] end_request: I/O error, dev sr1, sector 0
Nov 21 14:12:55 homebrew kernel: [109919.110560] Buffer I/O error on device sr1, logical block 0
Nov 21 14:19:08 homebrew kernel: [110292.748949] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.777627] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.806298] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.834972] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.863644] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.892311] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew kernel: [110292.920982] psmouse.c: bad data from KBC - timeout
Nov 21 14:19:08 homebrew k...

[N7DR (doc-evans)]

The lspci output file is attached.

[N7DR (doc-evans)]

It seems like this is now marked "Invalid". I don't understand why. What is invalid about the report? I am confused.

[N7DR (doc-evans)]

I am still awaiting an explanation of why this bug is supposedly "invalid". It's as easy as ever to demonstrate that the bug still exists. I see that a ton of people are subscribed to this bug, so can one of you *please* explain why it's "invalid"?

[kernel-janitor (kernel-janitor)]

Hi doc-evans,

This bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? Can you try with the latest development release of Ubuntu? ISO CD images are available from http://cdimage.ubuntu.com/releases/ .

If it remains an issue, could you run the following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux-image-`uname -r` 176370

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

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[Jeremy Foshee (jeremyfoshee)]

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release http://www.ubuntu.com/getubuntu/download . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]