Subject: Re: [linux-audio-dev] Re: costs of IPC
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Sun May 13 2001 - 20:50:36 EEST
On Sun, May 13, 2001 at 12:31:05PM -0400, Paul Davis wrote:
> just for reference sake, those of us interested in real-time systems
> with latencies on the order of 2.5ms and below have no more than 1.3ms
> to process an entire audio block. if "low" includes, say, 5 threads,
> you're proposing on the order of 10% of the total cycles available for
> processing be dedicated to inter-thread operations.
I think we're all agreed that we need <3ms latency for a good system, and
5 threads seems like a realistic number, but where is the 10% going to?
If its mostly due to cache emptying and refilling then it might not be
that much on an issue, domestic intel chips have very small caches and the
dsp part of each application is likly to fill it anyway.
OTOH if the 10% is is unaviodable kernel housekeeping then single thread
is the only real option for now.
- Steve
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