Roch - PAE wrote:
Sebastien Roy writes:
> Rajagopal Kunhappan wrote:
> > The tuning that you have done is rather weird. By default,
> > ip_squeues_per_cpu has a value of 1. But that does not mean that only
> > one squeue will be there for a CPU. More squeues upto a maximum of 32
> > can get allocated for a CPU and they get allocated on demand. So setting
> > ip_squeues_per_cpu to 32 is not very interesting.
> >
> > What is interesting is that you have set ip_soft_rings_cnt to 2 times
> > ip_squeues_per_cpu which would be 64 in your case. This does not seem
> > right.
> >
> > If you have a 64 CPU system and want to use all of them to process
> > incoming packets for a NIC, then it may just be ok, but having more soft
> > rings than the number of CPUs does not give you any performance advantage.
> >
> > My suggestion is to not change ip_squeues_per_cpu at all but tune
> > ip_soft_rings_cnt only. Set it to 2 or 3 for 1Gbps NIC and anywhere from
> > 16 to 32 for 10 Gbps NIC. Again don't increase the soft ring count to
> > more than the number of CPUs in the system. Also note that CPU speed is
> > also important in the calculation. A simple rule of thumb is that a 1Ghz
> > CPU should be able to handle a 1Gbps NIC.
>
> Could all of this manual tuning be made obsolete by some simple
> heuristics in the code which could automatically set these things? The
> number of CPUs on the system is no secret to the kernel. Will any of
> the ongoing projects (such as Crossbow or PEF) make this situation better?
>
For now, I don't understand why fanout is not happening. The
connections are not established in one swoop and so the flow
should spread to multiple squeues (ip_squeues_fanout=1). Why
is this not happening ?
ip_squeue_fanout knob was not set initially and it is not a Niagara
system (so fanout is not default). This is my reading.
-krgopi
-r
> -Seb
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