Messages in this thread | | | Date | Sat, 5 Jan 2002 15:46:14 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: [announce] [patch] ultra-scalable O(1) SMP and UP scheduler |
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On Sat, 5 Jan 2002, Alan Cox wrote:
> > > 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.
Yep true, 20% of CPUs are dumb but this 20% of CPUs run 95% of the Linux world.
> > 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, near to my box i've a dual cpu appliance that is running an mta that uses pthread and that is routing ( under test ) about 600000 messages / hour Its rq load is about 9-10 and the cs is about 8000-9000. You know what is the scheduler weight, barely 8-10% with the the 2.4.17 scheduler. It drops to nothing using BMQS w/out any O(1) mirage.
- Davide
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