On Tue, 7 Feb 2012 19:54:11 +0100 Marek Kierdelewicz <marek@xxxxxxxxx> wrote: > >> Can anyone point me to some performance comparison of netfilter on > >> i686 and x86_64? I have a few linux routers doing a lot of > >> firewalling and QoS. Currently those routers use i686 arch on 64-bit > >> hardware. Would I notice any performance gain after moving to 64-bit > >> kernel? > > >Apart from the obvious "Try it on your workload and see." suggestion, > >you could I suppose make the assumption that a netfilter workload > >looks similar to one or more components of something like > > Thanks for the response. Anyway moments ago I found answer to the first > question on vyatta forum here: > http://www.vyatta.org/forum/viewtopic.php?t=823&sid=3cec85f2cf7866ca26040ec491415ee1 That information is out of date. The bulk of the slow down in 64 bit was due to the fact that IOMMU (CONFIG_DMAR) was enabled. The IOMMU requires programming DMA registers on each packet which explains the extra overhead. After disabling DMA remapping, the 64 bit kernel is faster because the compiler has more registers and can generate better code. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
