On Sat, 10 Jul 2004 14:15:47 +0200 Florian Schmidt <[EMAIL PROTECTED]> wrote:
> Hi, chiming in late. I experienced the same. When i booted into the patched kernel > voountary_preemption was on. But when i tried to turn on kernel_preemption, too, it > immeaditly crashed.. will try your new patch now.. Ok, no more crashing, but i don't see any substantial improvement either. Actually i'm not sure i saw any improvement. I use JACK with a periodsize of 512 frames. At a framerate of 48khz this equals a time of 512/48000secs = 0.010667secs. So basically jack has about 10msecs to produce the next period while another one is playing. But: No matter which 2.6.x kernel i use i always can trigger xruns by either 1] many window manager ops [like rapid desktop wheeling in fluxbox] 2] compiling a kernel in some other term Mind you i talk about just jackd alone, no clients connected, etc, same thing as user and as root. As root it doesn't even make a difference if i export LD_ASSUME_KERNEL in jackd's process.. And yes, jackd runs in th SCHED_FIFO scheduling class with no other SCHED_FIFO process fighting for cpu time.. mango:~# LD_ASSUME_KERNEL=2.4.19 jackd -R -d alsa -p512 jackd 0.98.1 Copyright 2001-2003 Paul Davis and others. jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details loading driver .. creating alsa driver ... hw:0|hw:0|512|2|48000|0|0|nomon|swmeter|-|32bit control device hw:0 configuring for 48000Hz, period = 512 frames, buffer = 2 periods Couldn't open hw:0 for 32bit samples trying 24bit instead Couldn't open hw:0 for 24bit samples trying 16bit instead Couldn't open hw:0 for 32bit samples trying 24bit instead Couldn't open hw:0 for 24bit samples trying 16bit instead **** alsa_pcm: xrun of at least 0.057 msecs **** alsa_pcm: xrun of at least 0.033 msecs **** alsa_pcm: xrun of at least 0.117 msecs Behviour was substantially better with 2.4.x + ll + preempt. I could compile a kernel, do other stuff AND run an ardour session with 4 tracks w/o xruns at all for hours.. So, i hope that maybe you, Ingo, know a way on how to provide more useful info for you kernel development people. I read somewhere about ALSA's xrun debugging. Which kernel options and boottime parameters do i need for this? Is there a sysctl to switch it on? What file is the log dumped, too.. I also read on lkml about some latency Instrumentation patch for the 2.6.x kernels to find out where kernel latencies are happening.. Maybe you can provide a simple howto on how to use all that stuff to provide better infos for you.. Maybe the best is to assume that we start out with a clean 2.6.7 vanilla kernel source. Please tell us which patches to apply to get useful results. thanks for all the great kernel work btw. You guys rock! :) Florian Schmidt -- Palimm Palimm! http://affenbande.org/~tapas/wiki
