MOTU Fastlane MIDI driver wastes 10-25% CPU
MOTU Fastlane MIDI driver wastes 10-25% CPU
- Subject: MOTU Fastlane MIDI driver wastes 10-25% CPU
- From: Shaun Wexler <email@hidden>
- Date: Thu, 07 Nov 2002 04:56:30 -0800
Hello group,
Well, MOTU hasn't quite got it with their beta USB-MIDI driver, methinks:
From within Process Viewer, the MIDIServer itself averages 10-25% of total
CPU capacity on a B&W 500 G3, using the most recent MOTU Fastlane USB-MIDI
driver (1.0.0-Beta5, current as of 10/31/02). Any ideas? It9s blocking is
inconsistent, and totally unusable. 50% of its thread time is spent in the
kernel, mainly blocking, but also fighting various locks, vm, and wait
queues. Doesn9t matter which particular MIDI app spawns the MIDIServer, nor
which USB port/hub or device connections are used. How heavy should the
MIDIServer thread(s) REALLY be taxing the system with a normal STABLE
driver, as an estimate of total CPU%? I9ve got frame-rate intensive
displays and many FFT threads competing for every spare cycle...
Any recommendations for a more reliable bus-powered 2x2 USB interface for OS
X 10.2? Most of the MIDI support coding isn9t in my schedule for about
another 30 days (though I9ve been tinkering with it), so I have time to
exchange the Fastlane for something that works better with Jaguar.
I also have another problem. I need to be able to transmit raw MIDI packets
over a USB-to-serial interface, to external RS-232 or 422/485 devices. It
looks like I need to plan to write my own internal classes, rather than an
IOKit driver or kext. Are there timing issues to consider, or do I just use
the serial port9s nominal speed and read/write the raw streams? Am I
missing something? Would polling be necessary to read from the port?
TIA for any insights.
--
Shaun Wexler,
MacFOH
BTW, I9m writing the companion app which would use the CoreAudio kext
plug-ins mentioned by Mark Ketilson in an earlier thread. I think it9s
easily possible to avoid the plug-in altogether, and map the input and
phantom power switching to separate standard HAL data sources, so all apps
can access them. The plug-in would only work with my app, and others who
wrote device-specific implementations for it.
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