Re: 2.6 vs 2.4 regression when running gnomemeeting

Nick Piggin
2003-12-20T00:49:08Z

Christian Meder wrote:

>On Sat, 2003-12-20 at 01:21, Nick Piggin wrote:
>
>>Christian Meder wrote:
>>
>>
>>>On Fri, 2003-12-19 at 21:32, William Lee Irwin III wrote:
>>>
>>>
>>>>On Fri, Dec 19, 2003 at 09:11:50PM +0100, Christian Meder wrote:
>>>>
>>>>
>>>>>I've got a longstanding regression in gnomemeeting usage when switching
>>>>>between 2.4 and 2.6 kernels.
>>>>>Phenomenon:
>>>>>Without load gnomemeeting VOIP connections are fine. As soon as some
>>>>>load like a kernel compile is put on the laptop the gnomemeeting audio
>>>>>stream is cut to pieces and gets unintelligible . On 2.4.2x I don't get
>>>>>even the slightest distortion in the audio stream under load. I played
>>>>>around with different nice levels with no success. The problem persisted
>>>>>during the whole 2.6.0-test series no matter whether I used -mm kernels
>>>>>or pristine Linus kernels. Even when nicing the kernel compile to +19
>>>>>the distortions start right away. I tried Nick Piggin's scheduler which
>>>>>fared slightly better after changing the nice level of gnomemeeting to
>>>>>-10 but it's still a far cry from the 2.4.2x feeling without any
>>>>>fiddling with nice values.
>>>>>Any hints where to start looking are greatly appreciated.
>>>>>
>>>>>
>>>>Please instrument your workload with the following, and send logs of the
>>>>output (preferably compressed) to me and possibly others:
>>>>
>>>>top b d 5
>>>>vmstat 5
>>>>while true; do cat /proc/vmstat; sleep 5; done
>>>>while true; do cat /proc/meminfo; sleep 5; done
>>>>
>>>>A good way to log commands like this is:
>>>>
>>>>(command) > /home/foo.log.1 2>&1 &
>>>>
>>>>where parentheses surround the command in the actual shell input.
>>>>
>>>>
>>>Hi,
>>>
>>>I've attached the tarred output of a gnomemeeting run without load and
>>>without distortions and another tarred output of a gnomemeeting run
>>>while compiling a kernel with severe distortions in the audio stream.
>>>
>>>
>>You're getting a lot fewer interrupts in the loaded case. Maybe its
>>the sound card driver that has the regression from 2.4? It could be
>>that 2.6 allows a smaller sound fragment size which is more stressful.
>>
>>
>
>Well I had the same problem with the OSS driver on 2.6. Now I use the
>ALSA driver because I thought that could possibly improve things. The
>ALSA driver is better indeed but it doesn't change this particular
>phenomenon. Additionally I'd guess that the latest ALSA driver in 2.4
>and 2.6 doesn't differ significantly and 2.4.2x with the latest ALSA
>works great while 2.6 doesn't.
>
>

Sounds reasonable. Maybe its large interrupt or scheduling latency
caused somewhere else. Does disk activity alone cause a problem?
find / -type f | xargs cat > /dev/null
how about
dd if=/dev/zero of=./deleteme bs=1M count=256

You said it faired slightly better with my scheduler when renicing
gnome meeting to -10. How much better is that?

whats your /proc/cpuinfo?