On Sat, 2004-10-02 at 17:31, Florian Schmidt wrote: > On Sat, 02 Oct 2004 16:58:57 -0400 > Lee Revell <rlrevell@xxxxxxxxxxx> wrote: > > > Hey, > > > > I have been helping this user get set up with 2.6+VP, and it really > > looks like the kernel is not the problem - the maximum latency > > reported by Ingo's tracer is under 200 usecs, but there are still > > xruns. All my tests show that it should work at 128 or even 64 frames > > with this setup. It really looks like jackd or the jack clients are > > the problem. > > > > One could rule this out by writing a minimal alsa app which does nothing > but writing/reading from an alsa device. Make it sched_fifo, mlock its > memory, and register the alsa xrun callback [if such a thing exists, i > know very little alsa_pcm programming]. Then see if it experiences > xruns, too. If not, then jackd is probably to blame. > > Also maybe the alsa drivers themselfes might be problematic/buggy. If > the above minimal alsa app still produces xruns, then either alsa lib or > the drivers themselfes are to blame [probably]. > > Of course such a test is not a proof but might give important clues. I think we have ruled out the kernel. The problem has to be with jackd. the jack clients, alsa driver, or hardware. Here is the histogram from amlat 4096 + rtc-debug patch: rtc histogram: 17 7414 18 36139 19 3320 20 1719 21 1284 22 2480 23 3366 24 3529 25 3583 26 4713 27 9092 28 20543 29 39284 30 68270 31 98382 32 116862 33 127533 34 118842 35 85424 36 51875 37 29316 38 18818 39 16761 40 16627 41 12118 42 7723 43 6542 44 7971 45 9549 46 8433 47 4067 48 1571 49 876 50 840 51 1317 52 2332 53 3535 54 4304 55 4215 56 4604 57 4588 58 3559 59 2464 60 1863 61 1644 62 1203 63 805 64 543 65 445 66 490 67 473 68 438 69 237 70 141 The system was heavily loaded with parallel builds and find *'s, and the maximum reported latency is 70 usecs. Lee
