Messages in this thread | | | Date | Wed, 29 Dec 2004 22:08:45 -0500 | From | Bill Davidsen <> | Subject | Re: Kernel Benchmarks With P4+SMP+SMT? |
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Justin Piszcz wrote: > Has anyone performed any benchmarks with: > > No SMP w/HT? > SMP w/HT? > SMP + SMT w/HT? > > [ ] Symmetric multi-processing support > [ ] SMT (Hyperthreading) scheduler support > > x SMT scheduler support improves the CPU scheduler's decision making > x when dealing with Intel Pentium 4 chips with HyperThreading at a > x cost of slightly increased overhead in some places. If unsure say > x N here. > > I'm tempted to try SMT and benchmark these sometime but I am asking the > list if anyone has already done this first. > > Question: "slightly increased overhead in some places." > > What type of workloads would exhibit such overhead? > > Would this option (SMT) be recommended for a desktop or server machine? > > Are there any white papers or documentation I can read about this option?
I run SMT on all my HT uni systems. Depending on what you do it can help up to 30% (kernel build) or just enough to measure. This is one of those "it depends" things, I bet there are loads which run better without, and there is a tad of overhead in the SMP kernel locking.
If you run SMP, you have that overhead anyway, so I doubt it hurts.
YMMV
-- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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