Re: [alsa-devel] Re: AMIGA will use Linux, but Linux has several

Christopher T. Lansdown (lansdoct@screech.cs.alfred.edu)
Sat, 10 Jul 1999 11:21:48 -0400 (EDT)


I'm not well versed in these issues, so normally I wouldn't have said
anything, but...

> It's not a bug, it's a feature. "Optimize" will mean "screw normal usage".
Does "normal usuage" really mean "preempted for prolonged period of time
by disk usuage"?

The issue isn't quite being able to do ultra-realtime stuff (like Irix,
which is also a time sharing unix, can do), but more of letting
non-interacting non-interfering stuff run concurrently. I thought that
someone had tracked this problem down to the buffer flushing daemon making
a big kernel lock which prevented anything else from happening in that
time, which is just plain wrong. Disk activity shouldn't interfere with
audio activity. That's just bad timesharing if two unrelated activities
strongly interfere with each other.

I may be wrong about what the nature of the problem is, but it's
hard to believe that one activity (syncing) can significantly block
another (audio), when the two are completely unrelated. Since the audio
process will just read and write from a character device it has no
interaction with the hard drive after the /dev/dsp or whatever has been
opened, so why is the hard drive interfering with the audio? That just
seems like bad time sharing.
Of course, aren't they working on making as many subsystems of the
linux kernel multi-threaded with fine-grained locking so that stuff like
this shouldn't happen?
-Chris

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