Re: [announce] [patch] ultra-scalable O(1) SMP and UP scheduler

[Alan Cox <alan _at_ lxorguk.ukuu.org.uk>]

> > In fact it's the cr3 switch (movl %0, %%cr3) that accounts for about 30%
> > of the context switch cost. On x86. On other architectures it's often
> > much, much cheaper.
> 
> TLB flushes are expensive everywhere, and you know exactly this and if you

Not every processor is dumb enough to have TLB flush on a context switch.
If you have tags on your tlb/caches it's not a problem.

> Again, the history of our UP scheduler thought us that noone has been able
> to makes it suffer with realistic/high not-stupid-benchamrks loads.

Apache under load, DB2, Postgresql, Lotus domino all show bad behaviour. 
(Whether apache, db2, and postgresql want fixing differently is a seperate
 argument)

Alan
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