Messages in this thread | | | Date | Wed, 8 Dec 2004 14:08:45 +0100 | From | Karsten Desler <> | Subject | Re: _High_ CPU usage while routing (mostly) small UDP packets |
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* Willy Tarreau wrote: > On Tue, Dec 07, 2004 at 12:21:39PM +0100, Karsten Desler wrote: > > > > I also notice that a lot of time is spent allocating > > > and freeing the packet buffers (and possible hidden > > > time due to cache misses due to allocating on one > > > CPU and freeing on another?). > > > How many [RT]xDescriptors do you have configured by the way? > > > > 256. I increased them to 1024 shortly after the profiling run, but > > didn't notice any change in the cpu usage (will try again with cyclesoak). > > Have you checked the interrupts rate ? I had an e1000 eating many CPU cycles > because it would generate 50000 interrupts/s. Passing the module > InterruptThrottleRate=5000 definitely calmed it down, and more than doubled > the data rate.
I was running mit ITR=3000, but as a test to see if NAPI works, I disabled ITR on eth0 bringing the int/s rate up to 50k. Is that normal? I always though NAPI was supposed to kick in way earlier. Anyways, I'm going to try different ITR settings to see if they make any difference.
Cheers, Karsten - 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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