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Date: Fri, 11 Jan 2008 19:36:54 +0200 From: "Denys Fedoryshchenko" <denys@...p.net.lb> To: netdev@...r.kernel.org Subject: Re: e1000 performance issue in 4 simultaneous links Maybe good idea to use sysstat ? http://perso.wanadoo.fr/sebastien.godard/ For example: visp-1 ~ # mpstat -P ALL 1 Linux 2.6.24-rc7-devel (visp-1) 01/11/08 19:27:57 CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/s 19:27:58 all 0.00 0.00 0.00 0.00 0.00 2.51 0.00 97.49 7707.00 19:27:58 0 0.00 0.00 0.00 0.00 0.00 4.00 0.00 96.00 1926.00 19:27:58 1 0.00 0.00 0.00 0.00 0.00 1.01 0.00 98.99 1926.00 19:27:58 2 0.00 0.00 0.00 0.00 0.00 5.00 0.00 95.00 1927.00 19:27:58 3 0.00 0.00 0.00 0.00 0.00 0.99 0.00 99.01 1927.00 19:27:58 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 > >> > >>> When I run netperf in just one interface, I get 940.95 * 10^6 bits/sec > >>> of transfer rate. If I run 4 netperf against 4 different interfaces, I > >>> get around 720 * 10^6 bits/sec. > >>> > >> I hope this explanation makes sense, but what it comes down to is that > >> combining hardware round robin balancing with NAPI is a BAD IDEA. In > >> general the behavior of hardware round robin balancing is bad and I'm > >> sure it is causing all sorts of other performance issues that you may > >> not even be aware of. > >> > > I've made another test removing the ppc IRQ Round Robin scheme, bonded > > each interface (eth6, eth7, eth16 and eth17) to different CPUs (CPU1, > > CPU2, CPU3 and CPU4) and I also get around around 720 * 10^6 bits/s in > > average. > > > > Take a look at the interrupt table this time: > > > > io-dolphins:~/leitao # cat /proc/interrupts | grep eth[1]*[67] > > 277: 15 1362450 13 14 13 14 15 18 XICS Level eth6 > > 278: 12 13 1348681 19 13 15 10 11 XICS Level eth7 > > 323: 11 18 17 1348426 18 11 11 13 XICS Level eth16 > > 324: 12 16 11 19 1402709 13 14 11 XICS Level eth17 > > > > > > I also tried to bound all the 4 interface IRQ to a single CPU (CPU0) > > using the noirqdistrib boot paramenter, and the performance was a little > > worse. > > > > Rick, > > The 2 interface test that I showed in my first email, was run in two > > different NIC. Also, I am running netperf with the following command > > "netperf -H <hostname> -T 0,8" while netserver is running without any > > argument at all. Also, running vmstat in parallel shows that there is no > > bottleneck in the CPU. Take a look: > > > > procs -----------memory---------- ---swap-- -----io---- -system-- ----- cpu------ > > r b swpd free buff cache si so bi bo in cs us sy id wa st > > 2 0 0 6714732 16168 227440 0 0 8 2 203 21 0 1 98 0 0 > > 0 0 0 6715120 16176 227440 0 0 0 28 16234 505 0 16 83 0 1 > > 0 0 0 6715516 16176 227440 0 0 0 0 16251 518 0 16 83 0 1 > > 1 0 0 6715252 16176 227440 0 0 0 1 16316 497 0 15 84 0 1 > > 0 0 0 6716092 16176 227440 0 0 0 0 16300 520 0 16 83 0 1 > > 0 0 0 6716320 16180 227440 0 0 0 1 16354 486 0 15 84 0 1 > > > > > > > If your machine has 8 cpus, then your vmstat output shows a > bottleneck :) > > (100/8 = 12.5), so I guess one of your CPU is full > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Denys Fedoryshchenko Technical Manager Virtual ISP S.A.L. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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