Re: 2.6 vs 2.4 regression when running gnomemeeting

Nick Piggin
2003-12-20T00:21:29Z

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.