Re: 2.6 vs 2.4 regression when running gnomemeeting

From: Nick Piggin (piggin_at_cyberone.com.au)
Date: 12/20/03

  • Next message: Pat Gefre: "Re: [PATCH] Updating our sn code in 2.6" 
    Date:	Sat, 20 Dec 2003 11:48:58 +1100
To: Christian Meder <chris@onestepahead.de>

    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?

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  • Next message: Pat Gefre: "Re: [PATCH] Updating our sn code in 2.6"

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