Messages in this thread | | | From | Andrew Theurer <> | Subject | Re: Linux 2.4.19-rc3 (hyperthreading) | Date | Mon, 29 Jul 2002 15:58:47 -0500 |
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On Monday 29 July 2002 4:28 pm, Alan Cox wrote: > On Mon, 2002-07-29 at 20:54, Andrew Theurer wrote: > > I would caution against having hyperthreading on by default in the 2.4.19 > > release. I am seeing a significant degrade in network workloads on P4 > > with hyperthreading on. On 2.4.19-pre10, I get 788 Mbps on NetBench, but > > on 2.4.19-rc1 (and probably rc3, should know in an hour), I get 690 Mbps. > > It is clearly a hyperthreading/interrupt routing issue. On this system > > (4 x P4), > > Quite possibly. I've just merged the O(1) scheduler load balancing fixes > for the hyperthreading stuff, rc3 uses the old scheduler so that isnt > your problem. For most workloads I see a speed up. The more cache > optimised the workload the less the speedup. > > Its quite possible the irq routing ought to be smarter, at the moment > I'm not sure of the best approaches.
Agreed, we need some sort of irqbalance, and I intend to test with Ingo's and Andrea's approaches. With that addition, I may even see an improvement with hyperthreading. But for an rc release, I think it would be prudent to revert the "new code" for default hyperthreading behavior, and attack the whole problem in 2.4.20 or later release.
-Andrew Theurer
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