Subject: Re: [linux-audio-dev] Re: costs of IPC
From: Kai Vehmanen (kaiv_AT_wakkanet.fi)
Date: Sun May 13 2001 - 04:11:49 EEST
On Sat, 12 May 2001, Abramo Bagnara wrote:
> This thread is becoming more and more instructive ;-)
Yes indeed! But I think you've forgotten one aspect of this IPC issue: how
the audio system (= referring to the whole single/multi-threaded/process
system) behaves under heavy load?
As I've mentioned in my earlier message today, multiple threads means
multiple deadlines. Even if we assume IPC has zero cost, scheduling is
still a problem. If you have 30 threads/processes participating in the
audio processing, that means each of those threads must get enough
processor time during the <5ms timeframe we have...
Now I'm not saying it's impossible to have those 30 threads. It might be
that by using user-space threads (or something else that gives you control
over thread scheduling) might enable you to solve the problem. I've
understood that gstreamer does something along these lines. But you can't
deny that it's much easier and simpler to solve the problem by running one
thread with sched_fifo priority...
-- http://www.eca.cx Audio software for Linux!
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