One thing you can do is make sure you tune your disk writes. I have noticed that I get the best results when pdflush is almost constantly running. There is a ton of info out there about what you can tweak but take a look at vm.dirty_ratio and vm.dirty_background_ratio.
You have to play with these settings until you find what works best for your system. Thanks Mike > On Mar 27, 2015, at 7:47 AM, Michał Purzyński <[email protected]> > wrote: > > Hello. > > I went through a massive number of documents regarding the netsniff itself, > including reading code of both the application, libpcap and kernel parts, > intel manuals for X520 and CPUs. Enough of reading, let's do something. > > How to tune netsniff-ng for the maximum performance? Question seems trivial, > answer is not so. Feel free to correct me. X520 and a few gbit/sec and a NUMA > (Sandy Bridge) system is what I have here. > > For the best cache utilisation, netsniff-ng should be on the same core that > card delivers packets to. With IO/AT and DCA we could have something like > this: > > -- packets --> card --> cpu cache --> netsniff-ng > > It makes sense with DCA, actually. > > Now, does it mean we want RSS disabled and a single queue pinned to a single > core? > > Won't the number of interrupts (even using interrupt mitigation that's in the > ixgbe driver) kill the single core? > > Alternatively (I have only 2.0Ghz CPU and that's not enough to keep up with > the load from interrupts and netsniff-ng together on the same core) - > interrupts on core1, netsniff-ng on core2 (we're talking physical cores from > the same socket). > This will generate L1 and L2 miss most of the time but we still have L3 > that's inclusive (and huge). Win? > > With the kernel parameters "nohz_full=1-23 isolcpus=1-23" scheduler will keep > other tasks off the cores (1-23) by setting affinity on the init process and > disable ticks on them if there is a single task running (other kernel threads > can be set to run on core 0). > > What gives the best write performance - sg or mmap? > > -- > You received this message because you are subscribed to the Google Groups > "netsniff-ng" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "netsniff-ng" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
