Messages in this thread | | | Subject | Re: scheduler interactivity: timeslice calculation seem wrong | From | Eric St-Laurent <> | Date | Tue, 19 Aug 2003 02:54:03 -0400 |
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> So, if you give low priority processes bigger timeslices than high prio > ones, the low priority processes will be allowed to consume more CPU than > high. Obviously not the intended result. I agree with your intended result,
Thanks for the crystal clear explanation.
that 'switched-arrays timeslice distribution' is good for fairness but maybe it add unwanted scheduling latency to a high priority task that sit with it's timeslice expired...
i know it's more a real-time os thing, but i always liked the concept of pure priority scheduling with priority boost (calculated from aging) to prevent starvation. in a multi-level feedback queue scheduler, a processor share percentile could be assigned to each priority level. anyway i'm sure there is some proven fair-share scheduling algos out there that's better than this old stuff.
> I don't think you need that much grainularity. Might be a benefit though.
personally, i not a fan of the jiffies/tick concept; conversions, lost ticks problems, drifts, sub-tick high-res-posix-timers etc. everything should use the highest resolution timer/counter in the system (TSC, ACPI PM counter, ...) directly. it's a major cleanup and many old PCs don't have the newer timers.
> >- lastly, it may be usefull to better encapsulate the scheduler to ease > >adding alternative scheduler, much like the i/o schedulers work...
Well, i was looking at TimeSys scheduler, trying something like that in 2.6 requires modifications to many files and it's a PITA to maintain a diff with frequents kernel releases. having a structure in place to plug-in other schedulers sure helps.
Eric St-Laurent
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