Messages in this thread | | | From | (Davide Libenzi) | Subject | Re: O(1) scheduler | Date | Mon, 31 May 1999 09:09:33 +0200 |
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>>The run-priority of processes is determined by fine-grain time >>accounting. The scheduler would read the RTSC register (or the timer >>chip internal counter on pre-Pentium processors) once each time it needs >>rescheduling, and decrease the time budget of the currently active by >>the amount of time the process has been run. If the integer part (run >>priority) decreases, the process has to be moved to another bucket, and >>there is inserted at the front. Now the scheduler would schedule the >>first process in the highest bucket. > >This has some problems: > >- old CPUs that don't have a TSC, so you need a fall back. >- the standard TSC counts interrupts and bottom halves too. It would >be unfair to charge them to a process (I believe the SMP scheduler in 2.2 >has the same problem)
I think the idea is good, even if We don't have a TSC ( We can count timer tics for example ). The _really_ important deal is avoid linear scan of process list.
All this, is of course, IMVHO.
Cheers, Davide.
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