Messages in this thread | | | Date | Sat, 1 Oct 2011 20:40:49 +0200 | From | Willy Tarreau <> | Subject | Re: big picture UDP/IP performance question re 2.6.18 -> 2.6.32 |
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On Sat, Oct 01, 2011 at 02:16:05PM -0400, starlight@binnacle.cx wrote: > At 08:44 AM 10/1/2011 +0200, Eric Dumazet wrote: > >In my experience, I have the exact opposite : > >performance greatly improved in recent > >kernels. Unless you compile your kernel to include > >new features that might reduce performance > >(namespaces, cgroup, ...) > > RH has both of the above turned on in the > 2.6.32-71.29.1.el6.x86_64 kernel tested. > > If these are big negatives to network > performance, could you list what should > specifically turned off to maximize > results? Also a recommendation for > the best recent kernel for another > benchmark would be helpful. > > Probably can't convince anyone to deploy a > kernel without commercial support, but if > an alternate compile fixes performance it > might be possible to convince RH to support > the alternative build.
Just a suggestion, instead of measuring CPU usage at a given load, could you check what maximal load you can achieve ? It is very possible that CPU usage report is not accurate. We observed this in a number of situations, especially in high packet rate environments where the usage is a sum of many micro-measurements.
Also, I did not notice any indication on the load level you were reaching (packets per second and bandwidth). Have you compared the interrupt rate ? It is possible that they differ between the two kernels, for instance because the NIC auto-adapts instead of being throttled to a given rate. This can have a significant impact on measurements and performance.
Regards, Willy
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