Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context

[Eric Dumazet]

On Tue, Jan 9, 2018 at 5:36 AM, Dmitry Safonov <dima@xxxxxxxxxx> wrote:
> Warning: Not merge-ready
>
> I. Current workflow of ksoftirqd.
>   Softirqs are processed in the context of ksoftirqd iff they are
>   being raised very frequently. How it works:
>   do_softirq() and invoke_softirq() deffer pending softirq iff
>

...

>
>   Note, that I tested in VMs and I've found that if I produce more
>   hw irqs on the host, than the results for master are not that
>   dramatically bad, but still much worse then with RFC.
>   By that reason I have qualms if my test's results are correct.

Note that deferring all NET RX/TX to ksoftirqd is going to
dramatically hurt tail latencies.

You really should test with RPC like workloads (netperf -t TCP_RR) and
hundred of threads per cpu :/

It seems we are going to revert/adapt 4cd13c21b2 , not defer more
stuff to ksoftirqd.

Thanks