Messages in this thread | | | Date | Tue, 11 Jan 2005 11:17:02 -0800 | From | Matt Mackall <> | Subject | Re: [PATCH] [request for inclusion] Realtime LSM |
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On Tue, Jan 11, 2005 at 08:05:08AM -0500, Paul Davis wrote: > >> Running `nice --20' is still significantly worse than SCHED_FIFO, but > >> not the unmitigated disaster shown in the middle column. But, this > >> improved performance is still not adequate for audio work. The worst > >> delay was absurdly long (~1/2 sec). > > > >Let's work on that. It'd be _far_ better to have unprivileged near-RT > >capability everywhere without potential scheduling DoS. > > 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.
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.
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