On Mon, Jul 5, 2010 at 12:16 AM, Clemens Ladisch <[email protected]> wrote: > As long we're optimizing for benchmarks: In recent enough kernel > versions, Roland (Edirol/BOSS) USB MIDI devices have a mixer control > "MIDI Input Mode" (the same as the "Light Load" checkbox in the Windows > driver) which doesn't have much effect in practice but can improve > benchmark behaviour.
Note that for kernel 2.6.32.14-127.fc12.x86_64, and for ## snd-card-3 snd-usb-audio ## --> Emagic MT4 ## alias snd-card-5 snd-usb-audio ## --> Roland UM-2 ## ## amixer -c 5 --> returns nothing ## amixer -c 3 --> returns nothing Maybe the feature will be present in fedora 13? > For bulk transfers (used by Roland devices in "High Load" mode, and > always by all other devices), the UHCI driver has a feature called FSBR > (full-speed bandwidth reclamation) which makes the controller poll the > device continuously instead of every 1 ms, as long as new input is > available every 10 ms. So to get better benchmark numbers, use "-w 1" > instead of "-w 20". (If your music doesn't have new notes every 10 ms, > this isn't very realistic, but it can improve latency between the > consecutive notes of a chord.) Here's results for the Roland UM-2 with the argument suggested: ## sudo alsa-midi-latency-test -w 1 -r -R -i 36:0 -o 36:0 > alsa-midi-latency-test 0.0.3 > set_realtime_priority(SCHED_FIFO, 99).. done. > clock resolution: 0.000000001 s > interval between measurements: 1.000 .. 2.000 ms Test1) 2.1 - 2.2 ms: 488 ######################## 2.2 - 2.3 ms: 961 ############################################### 2.3 - 2.4 ms: 1023 ################################################## 2.4 - 2.5 ms: 1030 ################################################## 2.5 - 2.6 ms: 996 ################################################ 2.6 - 2.7 ms: 971 ############################################### 2.7 - 2.8 ms: 952 ############################################## 2.8 - 2.9 ms: 1013 ################################################# 2.9 - 3.0 ms: 1025 ################################################## 3.0 - 3.1 ms: 1013 ################################################# 3.1 - 3.2 ms: 518 ######################### 3.2 - 3.3 ms: 6 # 3.3 - 3.4 ms: 1 # ... 3.5 - 3.6 ms: 1 # 3.6 - 3.7 ms: 1 # ... 3.8 - 3.9 ms: 1 # best latency was 2.08 ms worst latency was 3.84 ms, which is great. .......................................... Test2) ... 2.1 - 2.2 ms: 479 ####################### 2.2 - 2.3 ms: 944 ############################################# 2.3 - 2.4 ms: 1034 ################################################# 2.4 - 2.5 ms: 1012 ################################################ 2.5 - 2.6 ms: 1006 ################################################ 2.6 - 2.7 ms: 985 ############################################### 2.7 - 2.8 ms: 913 ############################################ 2.8 - 2.9 ms: 1046 ################################################## 2.9 - 3.0 ms: 1021 ################################################# 3.0 - 3.1 ms: 1011 ################################################ 3.1 - 3.2 ms: 543 ########################## 3.2 - 3.3 ms: 3 # ... 3.4 - 3.5 ms: 2 # 3.5 - 3.6 ms: 1 # best latency was 2.07 ms worst latency was 3.55 ms, which is great. ............................ Last time, with "-w 20": Test1) best latency was 2.03 ms worst latency was 3.19 ms, which is great. Test2) best latency was 2.07 ms worst latency was 3.11 ms, which is great. -- Niels http://nielsmayer.com _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
