Messages in this thread |  | | | Subject | Re: big picture UDP/IP performance question re 2.6.18 -> 2.6.32 | | From | Eric Dumazet <> | | Date | Sat, 01 Oct 2011 21:11:43 +0200 |
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Le samedi 01 octobre 2011 à 14:16 -0400, starlight@binnacle.cx a écrit : > 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. >
2.6.32 has a perf tool, that can really help to spot in a few minutes hot spots. That would definitely help to further diagnose what could be the problem in your workload.
A single patch can have huge performance impact, sometime not noticed.
For example, in 2.6.36, AF_UNIX support for pid namespaces dropped performance a lot [commit 7361c36c5224 (af_unix: Allow credentials to work across user and pid namespaces)], because of a single atomic operation, but done on each send() and receive() on a central location.
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