Messages in this thread | | | Subject | Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch | From | Lee Revell <> | Date | Mon, 12 Jul 2004 20:17:04 -0400 |
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On Mon, 2004-07-12 at 19:31, Andrew Morton wrote: > Lee Revell <rlrevell@joe-job.com> wrote: > > > > On Sun, 2004-07-11 at 01:25, Andrew Morton wrote: > > > What we need to do is to encourage audio testers to use ALSA drivers, to > > > enable CONFIG_SND_DEBUG in the kernel build and to set > > > /proc/asound/*/*/xrun_debug and to send us the traces which result from > > > underruns. > > > > > > > OK, here goes. The following traces result from running JACK overnight > > like so, on an otherwise idle system. Hardware is a VIA EPIA 6000, with > > a 600Mhz C3 processor. Kernel is 2.6.7 + volunatary_preempt patch. > > voluntary_preempt and kernel_preemption are both on. > > > > jackd -v --realtime -d alsa --outchannels 2 --rate 48000 --shorts > > --playback --period 32 --nperiods 2 > > > > These settings require less than 666 microseconds scheduler latency. > > The average performance is quite good - 5-20 *microseconds*! > > OK, thanks. The problem areas there are the timer-based route cache > flushing and reiserfs. > > We can probably fix the route caceh thing by rescheduling the timer after > having handled 1000 routes or whatever, although I do wonder if this is a > thing we really need to bother about - what else was that machine up to? >
Gnutella client. Forgot about that. I agree, it is not reasonable to expect low latency with this kind of network traffic happening. I am impressed it worked as well as it did.
> resierfs: yes, it's a problem. I "fixed" it multiple times in 2.4, but the > fixes ended up breaking the fs in subtle ways and I eventually gave up. >
Interesting. There is an overwhelming consensus amongst Linux audio folks that you should use reiserfs for low latency work. Should I try ext3?
Lee
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