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

[Dmitry Safonov]

On Thu, 2018-01-11 at 12:40 -0800, Linus Torvalds wrote:
> On Thu, Jan 11, 2018 at 12:34 PM, Dmitry Safonov <dima@xxxxxxxxxx>
> wrote:
> > 
> > I could try to write a PoC for that..
> > What should be the trigger to fall into workqueue?
> > How to tell if there're too many softirqs of the kind?
> 
> I suspect it would have to be time-based, probably using the
> scheduler clock.

I thought about this, but I was a bit afraid of how much pricey it
would be recalculate it each clock. Well, might just try to write that
and measure the impact.

> Most softirqs are really really small. So just counting them probably
> isn't all that meaningful, although the count is good as a fallback
> (as shown by the jiffy issues).
> 
> The good news is that we only have a fairly small handful of
> softirqs,
> so counting/timing them separately is still mainly a pretty small
> array (which needs to be percpu, of course).