From: Hubertus F. <fr...@us...> - 2000-11-20 20:23:39
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Ananth ..... I read the configurable scheduler white paper from HP. I thought it was a nice attempt to implement conviniently the cpu-affinity scheduling. There shortcomings at that point was that they basically allow to implement a different goodness value calculations only. I talked with the author at some point and he mentioned that he was thinking about multiple runqueues as an addon. The unfortunate think here is that Linus made rather strong negative comments regarding pluggable schedulers. -- Hubertus FROM: Rajagopal Ananthanarayanan DATE: 11/17/2000 13:59:52 SUBJECT: RE: [Lse-tech] Multiple Runqueues Mike Kravetz wrote: > > On Fri, Nov 17, 2000 at 07:55:04PM +0100, Andi Kleen wrote: > > On Fri, Nov 17, 2000 at 10:38:59AM -0800, Mike Kravetz wrote: > > > In my implementation we are trying to emulate the same > > > scheduling decisions that are made by the current Linux > > > scheduler. Because of this, we try to make `global` > > > > Why this emulation ? Do you fear to break existing programs ? > > We simply want to show what would happen if you go to multiple > runqueues. If we significantly change the behavior of the > scheduler, then it would be difficult to say what had the > greater impact: multiple runqueues or the change in behavior. Are there any thoughts about making the behavior of the scheduler configurable? For example, getting the real-time scheduler to work correctly can be tricky with multiple run-queues, since there is no single ordering entity. Relaxing the real-time scheduler to say that "thread with highest priority will be dispatched in < 1 millisecond" gives some leeway in designing distributed queues & their balancing. For harder real-time requirements this may be substituted with more stringent balancing algorithms, at the cost of basic scheduling complexity. Along similar lines there is some work at HP towards a plug-in scheduler. You might want to checkout: http://resourcemanagement.unixsolutions.hp.com/WaRM/schedpolicy.html |