Hi Ralf, You are comparing a banana and an orange to find out which one is sweeter. Given the nature of the problem it would help a lot to have as little differences between the systems under test, otherwise it's impossible to track it down.
I hazard a guess that it's Ubuntu's 2.6.32 realtime-preemt-kernel. There are no official 2.6.32 rt-patches and it's likely that some of the back/forward ports have screwed things up. Is 'cat /proc/interrupts' identical on both systems? what about 'ps ax | wc -l' and 'ps -eo pid,class,rtprio,ni,pri,pcpu,stat,comm --sort -rtprio' Are there high-priority jobs present on Ubuntu which are not on SuSE? What happens if you use the same kernel (SuSE's kernel on Ubuntu, or vice versa) but different disto user-lands? Is there still a difference in your measurements? ciao, robin On 07/11/2010 04:53 PM, Ralf Mardorf wrote: > Hi :) > > today I compared a default Ubuntu Studio with and without the > proprietary NVIDIA driver. Note that for Ubuntu Studio 2 tests failed > because of time out errors, but even the tests that were passed with > success are significantly less good, than the tests with openSUSE, were > I set up audio myself. > Ubuntu based Linux until now were my music Linux, e.g 64 Studio 3.0 and > 3.3, but I wonder if bad MIDI latency is depending to Ubuntu. > For Ubuntu Studio even PCI MIDI has got more jitter, but USB MIDI for > Suse, see older test in the archives. > > What might be the difference between Ubuntu and Suse? > > Could anybody compare different distros too? > > ------------------------------------------------------------------------ > Ubuntu Studio 10.04 amd64 > 2 x Terratec EWX 24/96 (2 single cards, but 1 virtual card) > Frequency scaling ? > ------------------------------------------------------------------------ > > spinymo...@ubuntu:~$ hwinfo --gfxcard > Driver: "nouveau" > Driver Modules: "drm" > IRQ: 18 > spinymo...@ubuntu:~$ alsa-midi-latency-test -l > Port Client name Port name > 14:0 Midi Through Midi Through Port-0 > 16:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 20:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 128:0 TiMidity TiMidity port 0 > 128:1 TiMidity TiMidity port 1 > 128:2 TiMidity TiMidity port 2 > 128:3 TiMidity TiMidity port 3 > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o20:0 -i20:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 1.00 ms > worst latency was 1.97 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o20:0 -i20:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 1.00 ms > worst latency was 3.36 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.93 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.74 ms, which is great. > > spinymo...@ubuntu:~$ uname -a > Linux ubuntu 2.6.32-23-preempt #37-Ubuntu SMP PREEMPT Fri Jun 11 > 10:19:07 UTC 2010 x86_64 GNU/Linux > spinymo...@ubuntu:~$ envy24control > 0xcf00, irq 20, Master Clock int 44100 > > No envy24control for > 0xcb00, irq 21, Master Clock ? > > 20:0 opto S/PDIF out --> 16:00 opto S/PDIF in > > ------------------------------------------------------------------------ > Ubuntu Studio 10.04 amd64 > 2 x Terratec EWX 24/96 (2 single cards, but 1 virtual card) > Frequency scaling ? > ------------------------------------------------------------------------ > > spinymo...@ubuntu:~$ hwinfo --gfxcard > Driver: "nvidia" > Driver Modules: "nvidia" > IRQ: 18 > spinymo...@ubuntu:~$ alsa-midi-latency-test -l > Port Client name Port name > 14:0 Midi Through Midi Through Port-0 > 16:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 20:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 128:0 TiMidity TiMidity port 0 > 128:1 TiMidity TiMidity port 1 > 128:2 TiMidity TiMidity port 2 > 128:3 TiMidity TiMidity port 3 > pinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o20:0 -i20:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 1.00 ms > worst latency was 1.84 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o20:0 -i20:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 1.00 ms > worst latency was 1.27 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.92 ms, which is great. > > spinymo...@ubuntu:~$ alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.72 ms, which is great. > > spinymo...@ubuntu:~$ uname -a > Linux ubuntu 2.6.32-23-preempt #37-Ubuntu SMP PREEMPT Fri Jun 11 > 10:19:07 UTC 2010 x86_64 GNU/Linux > spinymo...@ubuntu:~$ envy24control > 0xcf00, irq 20, Master Clock int 44100 > > No envy24control for > 0xcb00, irq 21, Master Clock ? > > 20:0 opto S/PDIF out --> 16:00 opto S/PDIF in > > ------------------------------------------------------------------------ > openSUSE 11.2 amd64 > 2 x Terratec EWX 24/96 (2 single cards, but 1 virtual card) > Frequency scaling performance > ------------------------------------------------------------------------ > > spinymouse1...@suse11-2:~> su -c "hwinfo --gfxcard" > Driver: "nvidia" > Driver Modules: "nvidia" > IRQ: 18 > spinymouse1...@suse11-2:~> alsa-midi-latency-test -l > Port Client name Port name > 14:0 Midi Through Midi Through Port-0 > 16:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 24:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > spinymouse1...@suse11-2:~> alsa-midi-latency-test -l > Port Client name Port name > 14:0 Midi Through Midi Through Port-0 > 16:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > 24:0 TerraTec EWX24/96 TerraTec EWX24/96 MIDI > spinymouse1...@suse11-2:~> alsa-midi-latency-test -Rrw=2 -o24:0 -i24:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.07 ms, which is great. > > spinymouse1...@suse11-2:~> alsa-midi-latency-test -Rrw=2 -o24:0 -i24:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.08 ms, which is great. > > spinymouse1...@suse11-2:~> alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.06 ms, which is great. > > spinymouse1...@suse11-2:~> alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 >> alsa-midi-latency-test 0.0.3 >> set_realtime_priority(SCHED_FIFO, 99).. done. >> clock resolution: 0.000000001 s >> SUCCESS > > best latency was 0.99 ms > worst latency was 1.05 ms, which is great. > > spinymouse1...@suse11-2:~> uname -a > Linux suse11-2 2.6.31.6-rt19 #1 SMP PREEMPT RT Wed Nov 18 16:59:26 CET > 2009 x86_64 x86_64 x86_64 GNU/Linux > spinymouse1...@suse11-2:~> envy24control > spinymo...@ubuntu:~$ envy24control > 0xcf00, irq 20, Master Clock int 44100 > > No envy24control for > 0xcb00, irq 21, Master Clock ? > > 24:0 opto S/PDIF out --> 16:00 opto S/PDIF in > > I still have got some tests to do, e.g. a real test by listening to MIDI > music and I'll test what happens if two sound cards become one virtual > sound card, http://www.jrigg.co.uk/linuxaudio/ice1712multi.html and > before doing this I need to test if the second, new second hand card > from Ebay isn't broken for audio, resp. I'll compare the sound quality > for my old and the new Terratec EWX 24/96 sound card, before they become > one virtual sound card. > > Cheers! > > Ralf > _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev