linuxaudio.org

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:

quoted text
> 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 ?

> ------------------------------------------------------------------------

>

> spinymouse@ubuntu:~$ hwinfo --gfxcard

>   Driver: "nouveau"

>   Driver Modules: "drm"

>   IRQ: 18

> spinymouse@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

> spinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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

> spinymouse@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 ?

> ------------------------------------------------------------------------

>

> spinymouse@ubuntu:~$ hwinfo --gfxcard

>   Driver: "nvidia"

>   Driver Modules: "nvidia"

>   IRQ: 18

> spinymouse@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

> pinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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.

>

> spinymouse@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

> spinymouse@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

> ------------------------------------------------------------------------

>

> spinymouse11.2@suse11-2:~> su -c "hwinfo --gfxcard"

>   Driver: "nvidia"

>   Driver Modules: "nvidia"

>   IRQ: 18

> spinymouse11.2@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

> spinymouse11.2@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

> spinymouse11.2@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.

>

> spinymouse11.2@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.

>

> spinymouse11.2@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.

>

> spinymouse11.2@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.

>

> spinymouse11.2@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

> spinymouse11.2@suse11-2:~> envy24control

> spinymouse@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

>

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