Messages in this thread |  | | | Subject | Re: [PATCH] sched: avoid large irq-latencies in smp-balancing | | From | Eric St-Laurent <> | | Date | Wed, 07 Nov 2007 19:24:46 -0500 |
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On Wed, 2007-11-07 at 17:10 -0500, Steven Rostedt wrote: > > > > It would be nice if sched_nr_migrate didn't exist, really. It's hard to > > imagine anyone wanting to tweak it, apart from developers. > > I'm not so sure about that. It is a tunable for RT. That is we can tweak > this value to be smaller if we don't like the latencies it gives us. > > This is one of those things that sacrifices performance for latency. > The higher the number, the better it can spread tasks around, but it > also causes large latencies. > > I've just included this patch into 2.6.23.1-rt11 and it brought down an > unbounded latency to just 42us. (previously we got into the > milliseconds!). > > Perhaps when this feature matures, we can come to a good defined value > that would be good for all. But until then, I recommend keeping this a > tunable.
Why not use the latency-expectation infrastructure?
Iterate under lock until (or before...) the system global latency is respected.
- Eric
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