Re: a joint letter on low latency and Linux

[Paul Barton-Davis]

In message <[e-mail]>you write:
>> I ask you again, just as I asked Larry: if K was 10 seconds, would
>> anyone characterize this as "hard realtime" ? 
>
>Paul, what is your definition of "hard realtime"?

I don't have one. I don't think its helpful to try to use categories,
when its the actual numbers that matter. I have absolutely no doubt
that stock Linux 2.whatever can guarantee a response to some external
event within 10 seconds, short of a system crash or hardware
failure. Simultaneously, I would be suprised if it could ever manage a
response within 5usec, let alone guarantee it.

For me, the interesting question is not "is audio a hard realtime app
or not?", its "if the response time is (say) 3ms, can
<some-version-of-linux> guarantee it 99% of the time ?" (100% would be
better, but 99% will almost certainly do).

if you're going to define *any* guaranteed response as "hard
realtime", be my guest. you might even be right. i just don't think
thats any help in trying to figure out what to do about the kinds of
needs that "real time" audio+MIDI apps have.

--p