← Back to team overview

linaro-pkg team mailing list archive

[Bug 709245] Re: ARM SMP scheduler performance bug

 

I have no USB analyzer in my office. The 'git bisect' was one of the few
items remaining in my todo list. Thanks for your time.

-- 
You received this bug notification because you are a member of Linaro
Maintainers, which is the registrant for Linaro Linux.
https://bugs.launchpad.net/bugs/709245

Title:
  ARM SMP scheduler performance bug

Status in Linaro Ubuntu Evaluation Builds:
  Fix Released
Status in Linaro Linux:
  Fix Committed
Status in OEM Priority Project:
  Fix Released
Status in OEM Priority Project maverick series:
  Fix Released
Status in OEM Priority Project natty series:
  Fix Released
Status in OEM Priority Project oneiric series:
  Fix Released
Status in “linux-ti-omap4” package in Ubuntu:
  Fix Released
Status in “linux-ti-omap4” source package in Maverick:
  Fix Released
Status in “linux-ti-omap4” source package in Natty:
  Fix Released
Status in “linux-ti-omap4” source package in Oneiric:
  Fix Released

Bug description:
  Original Bug name: "panda: USB disk IO slow"

  This bug effects ARM Cortex A9 cores, snowball, nvidia, OMAP 4, and
  other Cortex A9 processors.  Problem is in Fedora ARM builds also so
  not limited to Ubuntu.

  My Panda's USB seems to be significantly slower than a Beagle C4.

  hdparm shows buffered reads as ~12MB/s on the Panda, and about ~20-25MB/s on a Beagle C4 from the same
  external Lacie USB disk.

  Kernel is 2.6.37-1002-linaro-omap

  Disk shows as:

  [    5.170440] scsi 0:0:0:0: Direct-Access     LaCie    d2 quadra             PQ: 0 ANSI: 4
  [    5.172546] sd 0:0:0:0: Attached scsi generic sg0 type 0
  [    5.175415] sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB)

  The board is otherwise idle during the test.

  Doing perf_2.6.37-12 record -a dd if=/dev/sda of=/dev/null bs=4096
  count=100000

  shows :
      81.41%         swapper  [kernel.kallsyms]     [k] default_idle
       6.33%              dd  [kernel.kallsyms]     [k] __copy_to_user
       0.94%         swapper  [kernel.kallsyms]     [k] cpu_idle
       0.51%              dd  [kernel.kallsyms]     [k] __make_request
       0.51%  perf_2.6.37-12  [kernel.kallsyms]     [k] __copy_from_user

  which suggests it's not CPU constrained.

  Dave

To manage notifications about this bug go to:
https://bugs.launchpad.net/linaro-ubuntu/+bug/709245/+subscriptions