[LAD] MIDI jitter - Today for 4 of 4 tests my USB device did pass all tests with success

Today my swissonic USB MIDInterface didn't fail the ALSA MIDI latency tests. There are 3 differences. 1. I didn't use 64 Studio 3.0-beta3 and I didn't use 64 Studio 3.3 alpha, but Suse 11.2 were the rt stuff isn't from the repositories, but self build. 2. Using another kernel version, the kernels for 64 Studio were older and newer, but the Suse kernel. 3. My PATA HDD is disconnected, it was connected and break some days ago, but anyway I had timing issues when the drive was new too. An additional note. Around 4 ms is what I got when I used 64 Studio and did record audio 'of the MIDI data' and then interpreted the waveforms visually. With this visually jitter around 4 ms, the audible result was unusable to produce music. Within the next days I'll get a SATA as replacement for the broken PATA and an opto-coupler adapter for my PCI audio device, then I will run the ALSA MIDI latency test again and much more important, I will do a test making music. I'm very sceptic regarding to the ALSA MIDI latency test, OTOH the PATA might have caused 7 ms and IIRC 19 ms too and visually interpretation might mistake because it's hard to find the start of waveforms in the noise. 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 20:0 USB Device 0x170b:0x11 USB Device 0x170b:0x11 MIDI 1 spinymouse11.2@suse11-2:~> alsa-midi-latency-test -Rrw20 -i20:0 -o20:0 sample; latency_ms; latency_ms_worst 0; 1.50; 1.50 1; 2.21; 2.21 58; 2.24; 2.24 1614; 2.27; 2.27 9999; 1.60; 2.27 ... 1.2 - 1.3 ms: 186 ######### 1.3 - 1.4 ms: 1017 ################################################# 1.4 - 1.5 ms: 1034 ################################################## 1.5 - 1.6 ms: 968 ############################################### 1.6 - 1.7 ms: 966 ############################################### 1.7 - 1.8 ms: 1004 ################################################ 1.8 - 1.9 ms: 1037 ################################################## 1.9 - 2.0 ms: 931 ############################################# 2.0 - 2.1 ms: 1034 ################################################## 2.1 - 2.2 ms: 1024 ################################################# 2.2 - 2.3 ms: 788 ###################################### 2.3 - 2.4 ms: 11 # best latency was 1.20 ms worst latency was 2.27 ms, which is great. spinymouse11.2@suse11-2:~> alsa-midi-latency-test -i20:0 -o20:0 sample; latency_ms; latency_ms_worst 0; 1.52; 1.52 1; 1.80; 1.80 2; 1.85; 1.85 3; 1.85; 1.85 4; 2.69; 2.69 11; 3.82; 3.82 26; 3.85; 3.85 40; 3.96; 3.96 9999; 1.99; 3.96 ... 1.4 - 1.5 ms: 2 # 1.5 - 1.6 ms: 18 # 1.6 - 1.7 ms: 10 # 1.7 - 1.8 ms: 15 # 1.8 - 1.9 ms: 68 # 1.9 - 2.0 ms: 475 ### 2.0 - 2.1 ms: 9204 ################################################## 2.1 - 2.2 ms: 111 # 2.2 - 2.3 ms: 45 # 2.3 - 2.4 ms: 13 # 2.4 - 2.5 ms: 6 # 2.5 - 2.6 ms: 19 # 2.6 - 2.7 ms: 1 # 2.7 - 2.8 ms: 1 # ... 3.1 - 3.2 ms: 2 # 3.2 - 3.3 ms: 3 # 3.3 - 3.4 ms: 2 # 3.4 - 3.5 ms: 1 # ... 3.8 - 3.9 ms: 2 # 3.9 - 4.0 ms: 1 # 4.0 - 4.1 ms: 1 # best latency was 1.42 ms worst latency was 3.96 ms, which is great. Then I run glxgears with the window always on top and repeated the tests. spinymouse11.2@suse11-2:~> alsa-midi-latency-test -Rrw20 -i20:0 -o20:0 sample; latency_ms; latency_ms_worst 0; 1.68; 1.68 2; 2.16; 2.16 138; 2.17; 2.17 174; 2.19; 2.19 348; 2.20; 2.20 350; 2.20; 2.20 552; 2.21; 2.21 1708; 2.22; 2.22 3381; 2.24; 2.24 9999; 1.62; 2.24 ... 1.2 - 1.3 ms: 532 ########################## 1.3 - 1.4 ms: 1017 ################################################# 1.4 - 1.5 ms: 1010 ################################################ 1.5 - 1.6 ms: 980 ############################################### 1.6 - 1.7 ms: 1001 ################################################ 1.7 - 1.8 ms: 990 ################################################ 1.8 - 1.9 ms: 1010 ################################################ 1.9 - 2.0 ms: 952 ############################################## 2.0 - 2.1 ms: 1026 ################################################# 2.1 - 2.2 ms: 1042 ################################################## 2.2 - 2.3 ms: 440 ##################### best latency was 1.16 ms worst latency was 2.24 ms, which is great. While glxgears still was running I now moved windows by mouse too. spinymouse11.2@suse11-2:~> alsa-midi-latency-test -i20:0 -o20:0 sample; latency_ms; latency_ms_worst 0; 2.07; 2.07 263; 2.10; 2.10 441; 2.11; 2.11 446; 3.76; 3.76 9999; 1.99; 3.76 ... 1.2 - 1.3 ms: 4 # 1.3 - 1.4 ms: 3 # 1.4 - 1.5 ms: 7 # 1.5 - 1.6 ms: 5 # 1.6 - 1.7 ms: 7 # 1.7 - 1.8 ms: 3 # 1.8 - 1.9 ms: 19 # 1.9 - 2.0 ms: 204 # 2.0 - 2.1 ms: 9612 ################################################## 2.1 - 2.2 ms: 94 # 2.2 - 2.3 ms: 14 # 2.3 - 2.4 ms: 2 # 2.4 - 2.5 ms: 7 # 2.5 - 2.6 ms: 7 # 2.6 - 2.7 ms: 3 # 2.7 - 2.8 ms: 5 # 2.8 - 2.9 ms: 1 # ... 3.6 - 3.7 ms: 2 # ... 3.8 - 3.9 ms: 1 # best latency was 1.22 ms worst latency was 3.76 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