Re: Very bad interactivity with 2.6.0 and SCSI disks (aic7xxx)

[Nick Piggin <piggin@cyberone.com.au>]

Stefan Foerster wrote:

>[I've sent this mail aleready, but got an error from my MAILER-DAEMON.
>Perhaps ist was too large vor lkml, so I'm moving the oprofile output
>to a webserver]
>
>* Andrew Morton <akpm@osdl.org> wrote:
>
>>Stefan Foerster <stefan@stefan-foerster.de> wrote:
>>
>>>* Andrew Morton <akpm@osdl.org> wrote:
>>>
>>>>Stefan Foerster <stefan@stefan-foerster.de> wrote:
>>>>A kernel profile would be needed to diagnose this.  You could use
>>>>readprofile, but as it may be an interrupt problem, the NMI-based oprofile
>>>>output would be better.
>>>>
>>>Is this procedure documented anywhere?
>>>
>
>[every information I needed]
>
>I did the following steps:
>
>
>opcontrol --setup --vmlinux=/usr/src/linux/vmlinux --event=RETIRED_INSNS:100000:0:1:1
>
>Then I used your shell source:
>
>~/shells/oprofileit dd if=/dev/zero of=test bs=1024 count=1048576
>
>opreport -l  /usr/src/linux/vmlinux  > /tmp/1
>opreport -ld -D /usr/src/linux/vmlinux  > /tmp/2
>
>During the dd, again the xmms playing a file from an tmpfs froze and
>even screen redrawing was very, very slow.
>
>The output of these commands kan be found at:
>
>http://home.in.tum.de/foerstes/oprofile-1
>http://home.in.tum.de/foerstes/oprofile-2
>
>Is this information useful in debugging my problem, or should I go and
>try again with readprofile or other tools?
>

Nothing jumps out at me. Is your machine swapping during the bad behaviour?
What is the effect of echo 0 > /proc/sys/vm/swappiness, swapoff -a, or
using the deadline IO scheduler (boot with argument elevator=deadline)