At Mon, 09 Mar 2009 12:20:51 +0100, I wrote: > > At Mon, 9 Mar 2009 11:13:21 +0000, > Clive Messer wrote: > > > > On Tuesday 03 Mar 2009 17:41:22 Takashi Iwai wrote: > > > > > > Hrm, but still an unexpected jump is found. > > > > > > > > If you build the driver with CONFIG_SND_PCM_XRUN_DEBUG=y, you must > > > > have /proc/asound/card0/pcm0p/xrun_debug. Echo 1 to this (as root) > > > > echo 1 > /proc/asound/card0/pcm0p/xrun_debug > > > > and try the program, see whether any debug message appears. > > > > If any message appears, it means basically an unstable hardware. > > > > > > > > Also, the below is a patch I tried to clean up and improve the > > > > handling. Give it a try (and do echo 1 above for testing). > > > > > > BTW, the original test program is very hard to see what's wrong > > > because it spews out way too many lines. The below is a filtered-out > > > version. > > > > > > It prints only unexpected jumps of avail values (the threshold is > > > set 100 blindly). The output is like below: > > > > > > % ./alsa-time-test hw > > > 21720872 (4987) delta 216 avail 216 delay 4200 > > > 21943118 (65) delta 208 avail 208 delay 4208 > > > 23752310 (3) delta 232 avail 232 delay 4184 > > > 23761847 (5972) delta 264 avail 264 delay 4152 > > > > > > The first column is the usec from the program start, the next value in > > > parentheses is the time-step from the last time of status changes, > > > the delta is the increase of avail, and the rest are raw values. > > > > > > If a too large delta appears in a short time-step, something is wrong. > > > If it appears in a large time-step, it's simply a wrong responsiveness > > > (aka system latency). > > > > Hello Takashi/Lennart, > > > > Sorry, I have been busy for a few days. > > I patched my kernel (kernel-2.6.29-0.53.rc7.fc10.x86_64) with your pcm_lib.c > > patch and 'echo 1 > /proc/asound/card0/pcm0p/xrun_debug'. > > > > I have done several runs with the new alsa-time-test.c code. Typically I get a > > bunch of kernel dmesg when I start the alsa-time-test program but not > > afterwards. Just a reminder - I'm running this on fast hardware - X58 / Core > > i7 920 - the machine is not loaded at all, so latency should be very low. > > snd_hda_intel - ' 00-00: AD198x Analog : AD198x Analog : playback 1 : capture > > 3'. > > > > Here is an example run ..... > > > > hw_ptr skipping! (pos=2096, delta=2096, period=1472) > > hw_ptr skipping! (pos=2096, delta=2096, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > hw_ptr skipping! (pos=3600, delta=3600, period=1472) > > Thanks. This implies that the position pointer once reads zero > then the next value gets screwed up. It shows the DMA pointer > read is pretty unreliable on your hardware. It's obviously bad for > PA because the DMA pointer is the only trusted information for > glitch-free. For the traditional method, this isn't usually so > critical, though. > > > 9901323 (2632) delta 111 avail 117 delay 4299 > > 19901290 (2599) delta 112 avail 112 delay 4304 > > 29901285 (3) delta 112 avail 112 delay 4304 > > 39901315 (2624) delta 120 avail 120 delay 4296 > > 49901317 (2626) delta 112 avail 112 delay 4304 > > 59901317 (2625) delta 112 avail 112 delay 4304 > > 69901323 (2632) delta 118 avail 118 delay 4298 > > 79901391 (3) delta 120 avail 120 delay 4296 > > 89901327 (2634) delta 112 avail 112 delay 4304 > > 99901283 (2591) delta 120 avail 120 delay 4296 > > 109901334 (2642) delta 120 avail 120 delay 4296 > > 119901320 (2627) delta 112 avail 112 delay 4304 > > These outputs look fairly OK. The latency is about 2.5 ms and it's > about 110 samples. That us, as long as the outputs look like above, > your system is working fine with my patch. As the patch seems working with other tests, too, I merged it (with a slight clean-up) into sound git tree now. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
