Re: MOTU Fastlane MIDI driver wastes 10-25% CPU
Re: MOTU Fastlane MIDI driver wastes 10-25% CPU
- Subject: Re: MOTU Fastlane MIDI driver wastes 10-25% CPU
- From: Kurt Revis <email@hidden>
- Date: Fri, 8 Nov 2002 15:42:48 -0800
On Friday, November 8, 2002, at 03:04 PM, Doug Wyatt wrote:
On Thursday, Nov 7, 2002, at 23:23 US/Pacific, Kurt Revis wrote:
What I DO get are periodic spikes where the CPU usage goes up to 100%
for no apparent reason. This goes on for around fifteen seconds, and
happens every few minutes (it's happened 3 or 4 times while I've been
writing this). The MIDIServer's CPU usage bounces around between 50%
and 100%; most of this is shown as system time, not user.
Please open your console.log and /var/log/system.log and tell me
whether these periods of high usage correlate with log messages from
/usr/libexec/fix_prebinding.
Nope, I would have noticed that (although I did check again). Top
shows the CPU being used by the MIDIServer, not fix_prebinding.
When I run sample on the MIDIServer, here's the only interesting thread:
500 Thread_0f03
500 _pthread_body
500 XThread::RunHelper(void*)
500 DriverIOThread::Run()
500 CFRunLoopRunSpecific
500 __CFRunLoopRun
464 mach_msg
464 mach_msg_trap
464 mach_msg_trap [STACK TOP]
36 __CFRunLoopDoSource1
36 __CFMachPortPerform
36 IODispatchCalloutFromCFMessage
36 USBRead::ReadCallback(void*, int, void*)
36 USBInputPipe::ReadCompleted(USBRead*, int)
36 IsocUSBInputPipe::StartNewRead(USBRead*)
36 IsocUSBRead::DoRead(unsigned long long)
36
IOUSBInterfaceClass::ReadIsochPipeAsync(unsigned char, void*, unsigned
long long, unsigned long, IOUSBIsocFrame*, void (*)(void*, int, void*),
void*)
36 io_async_method_structureI_structureO
36 mach_msg
36 mach_msg_trap
36 mach_msg_trap [STACK TOP]
However, this looks exactly the same whether or not the CPU is spiking,
so the driver doesn't appear to be directly at fault.
Also, running Shikari during a spike shows the MIDIServer at about 5%
usage (pretty negligible) and the kernel taking up 70% of the time,
sitting in machine_idle_ret. But again, running it when there's no
spike gives essentially the same results.
So I suspect there's nothing really bad going on, just some sort of
weird anomaly in the kernel that causes it to erroneously report high
CPU usage. (Both top and the CPU Monitor app show the spike, BTW.)
But I could very easily be wrong!
At any rate, this appears to be completely different than the issue
Shaun is experiencing.
--
Kurt Revis
email@hidden
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