Messages in this thread | | | Subject | Re: BFS vs. mainline scheduler benchmarks and measurements | From | Mike Galbraith <> | Date | Thu, 10 Sep 2009 05:15:27 +0200 |
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On Wed, 2009-09-09 at 23:12 +0300, Nikos Chantziaras wrote:
> With your version of latt.c, I get these results with 2.6-tip vs > 2.6.31-rc9-bfs: > > > (mainline) > Averages: > ------------------------------ > Max 50 usec > Avg 12 usec > Stdev 3 usec > > > (BFS) > Averages: > ------------------------------ > Max 474 usec > Avg 11 usec > Stdev 16 usec > > > However, the interactivity problems still remain. Does that mean it's > not a latency issue?
Could be a fairness issue. If X+client needs more than it's fair share of CPU, there's nothing to do but use nice levels. I'm stuck with unaccelerated X (nvidia card), so if I want a good DVD watching or whatever eye-candy experience while my box does a lot of other work, I either have to use SCHED_IDLE/nice for the background stuff, or renice X. That's the down side of a fair scheduler.
There is another variant of latency related interactivity issue for the desktop though, too LOW latency. If X and clients are switching too fast, redraw can look nasty, sliced/diced.
-Mike
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