Messages in this thread | | | Date | Thu, 05 Jan 2006 15:31:17 +0100 | From | Mike Galbraith <> | Subject | Re: [PATCH] sched: Fix adverse effects of NFS client on interactive response |
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At 10:31 PM 1/5/2006 +1100, Peter Williams wrote: >Mike Galbraith wrote: >>At 08:51 AM 1/5/2006 +1100, Peter Williams wrote: >> >>>I think that some of the harder to understand parts of the scheduler >>>code are actually attempts to overcome the undesirable effects (such as >>>those I've described) of inappropriately identifying tasks as >>>interactive. I think that it would have been better to attempt to fix >>>the inappropriate identifications rather than their effects and I think >>>the prudent use of TASK_NONINTERACTIVE is an important tool for achieving this. >> >>IMHO, that's nothing but a cover for the weaknesses induced by using >>exclusively sleep time as an information source for the priority >>calculation. While this heuristic does work pretty darn well, it's >>easily fooled (intentionally or otherwise). The challenge is to find the >>right low cost informational component, and to stir it in at O(1). > >TASK_NONINTERACTIVE helps in this regard, is no cost in the code where >it's used and probably decreases the costs in the scheduler code by >enabling some processing to be skipped. If by its judicious use the >heuristic is only fed interactive sleep data the heuristics accuracy in >identifying interactive tasks should be improved. It may also allow the >heuristic to be simplified.
I disagree. You can nip and tuck all the bits of sleep time you want, and it'll just shift the lumpy spots around (btdt).
-Mike
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