Re: Packet time delays on multi-core systems
From: Alexey Vlasov
Date: Thu Sep 30 2010 - 08:25:25 EST
On Thu, Sep 30, 2010 at 08:33:52AM +0200, Eric Dumazet wrote:
> Le jeudi 30 septembre 2010 ?? 10:24 +0400, Alexey Vlasov a ??crit :
> > Here I found some dude with the same problem:
> > http://lkml.org/lkml/2010/7/9/340
> >
>
> In your opinion its the same problem.
>
> But the description you gave is completely different.
>
> You have time skew only when activating a particular iptables rule.
Well I put interrups from NIC, namely tx/rx query, to different
processors and got normal pings by adding LOG rule.
I also found that overruns is constantly growing, I don't know if these are connected.
RX packets:2831439546 errors:0 dropped:134726 overruns:947671733 frame:0
TX packets:2880849825 errors:0 dropped:0 overruns:0 carrier:0
Rather strange that only one processor was involved, even in top was
clear that ksoftirqd eats the first processor up to 100%.
Here goes the typical distribution of interrups on new servers:
CPU0 CPU1 CPU2 CPU3 ... CPU23
752: 11 0 0 0 ... 0 PCI-MSI-edge eth0
753: 2799366721 0 0 0 ... 0 PCI-MSI-edge eth0-rx3
754: 2821840553 0 0 0 ... 0 PCI-MSI-edge eth0-rx2
755: 2786117044 0 0 0 ... 0 PCI-MSI-edge eth0-rx1
756: 2896099336 0 0 0 ... 0 PCI-MSI-edge eth0-rx0
757: 1808404680 0 0 0 ... 0 PCI-MSI-edge eth0-tx3
758: 1797855130 0 0 0 ... 0 PCI-MSI-edge eth0-tx2
759: 1807222032 0 0 0 ... 0 PCI-MSI-edge eth0-tx1
760: 1820309360 0 0 0 ... 0 PCI-MSI-edge eth0-tx0
On the old ones:
CPU0 CPU1 CPU2 ... CPU8
502: 522320256 522384039 522327386 ... 522380267 PCI-MSI-edge eth0
--
BRGDS. Alexey Vlasov.
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