[ecasound] Re: Realtime priority (fwd)

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Subject: [ecasound] Re: Realtime priority (fwd)
From: Kai Vehmanen (kai.vehmanen_AT_wakkanet.fi)
Date: Thu May 16 2002 - 18:19:45 EEST


Some information about the -r switch and rt-scheduling in general:

---------- Forwarded message ----------
On Mon, 13 May 2002, XXX wrote:

> I don't know whether to use a positive or negative
> number of the -r option. If I really, really, want
> this to work right, can I use -r 10 ? Would that do
> it?

Just specifying -r (or -r:0) enables rt-scheduling and uses the default
priority-level (50, can be overridden in ~/.ecasound/ecasoundrc).
Otherwise you can specify a value between 1 and 99, where 99 is the max
priority-level.

It's good to note that specifying -r makes ecasound a realtime process.
Even with a low priority-level ecasound still gets more cpu-time than
normal processes (which use the default SCHED_OTHER kernel scheduling). So
adjusting the priority level is only important when you are running
multiple independent realtime processes. See 'man sched_setscheduler' for
more info about realtime scheduling in Linux.

To explicitly disable realtime scheduling, use -r:-1. For any of this to
work, you need to run ecasound as root (although in the future I might add
POSIX capabilities support to ecasound, which would make it possible to
use rt-scheduling without root-privileges).

-- 
 http://www.eca.cx
 Audio software for Linux!

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