Re: [RFC PATCH 0/5] softirq: Per vector threading v2

[Dmitry Safonov]

On Thu, 2018-01-18 at 05:09 +0100, Frederic Weisbecker wrote:
> On Wed, Jan 17, 2018 at 07:09:39PM -0800, Linus Torvalds wrote:
> > It should never trigger under any normal load, but I think it
> > *should*
> > trigger under the load that the networking people worry about. If
> > you
> > get a flood of UDP packets, and spend a lot of time in softirqs,
> > I'm
> > pretty sure you'd hit that case of seeing the same softirq re-
> > raised
> > fairly naturally and quickly.
> 
> Ok after a quick tracing check, it seems that executing the same
> softirq
> vector twice in the same interrupt does not happen without much
> stress.

Uhm, yes it should.. but that was what I originally saw on hw - that
raising a new softirq under UDP packet storm might happen slower than
expected. And a new softirq is raised only after the first one was
processed. Which results in rare deferring.

-- 
            Dima