Messages in this thread | | | Date | Sat, 20 Dec 2003 11:48:58 +1100 | From | Nick Piggin <> | Subject | Re: 2.6 vs 2.4 regression when running gnomemeeting |
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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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