Subject: Re: [linux-audio-dev] Re: costs of IPC
From: Paul Davis (pbd_AT_Op.Net)
Date: Sun May 13 2001 - 19:31:05 EEST
>For the example with 30 threads on my Dual PIII-800 it takes around 780us
>for a "ping". That's about 26us for a buffer to get in and out. For
>300(!) threads that increases to 32us. On a Celeron 300 Laptop it takes
>in total 1070us for 30 threads averaging to 35us, and looks quite worse
>for 300threads ->660us averaged. But anyway you wouldn't really want
>to run 300 threads. Compared to the execution time to actually process
>those buffers you can neglect the time to switch between single
>effect threads as long as you keep the thread count low.
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'm afraid that's not part of my worldview right now.
--p
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