Re: [PATCH] [request for inclusion] Realtime LSM

Jack O'Quin
2005-01-11T19:46:35Z

> On Tue, Jan 11, 2005 at 08:05:08AM -0500, Paul Davis wrote:
>> I am not sure what you mean here. I think we've established that
>> SCHED_OTHER cannot be made adequate for realtime audio work. Its
>> intended purpose (timesharing the machine in ways that should
>> generally benefit tasks that don't do a lot and/or are dominated by
>> user interaction, thus rendering the machine apparently responsive) is
>> really at odds with what we need.

Matt Mackall <mpm@selenic.com> writes:
> We have not established that at all. In principle, because SCHED_OTHER
> tasks running at full priority lie on the boundary between SCHED_OTHER
> and SCHED_FIFO, they can be made to run arbitrarily close to the
> performance of tasks in SCHED_FIFO. With the upside that they won't be
> able to deadlock the machine.
>
> And I mean arbitrarily close in the strict delta-epsilon sense.
> It's not perfect, but neither is SCHED_FIFO, in principle or in
> practice.

Though inelegant in theory, SCHED_FIFO *has* been shown to work in
practice. The POSIX 1003.4 committee were not all a bunch of idiots.
That stuff *is* useful and *does* work (given appropriate privileges).

Your assertions have not been reduced to practice. This is a
significant difference. Write some code, then we can discuss whether
it solves any problems or not. I doubt it, but prove me wrong and
next year you can be the proud author of a scheduler used for hundreds
of audio applications.

Meanwhile, what about 2005? It's "almost upon us". :-/
--
joq