On Mon, 2017-12-18 at 18:00 +0100, Mike Galbraith wrote:
> On Mon, 2017-12-18 at 11:35 -0500, J. Bruce Fields wrote:
> >
> > Like I say, I don't really understand the issues here, so it's more a
> > question than an objection.... (I don't know any reason a
> > cond_resched() would be bad there.)
>
> Think of it this way: what all can be queued up behind that kworker
> that is hogging CPU for huge swaths of time? It's not only userspace
> that suffers.
Bah, I'm gonna sound like a damn Baptist preacher, but I gotta say,
latency matters just as much to an enterprise NOPREEMPT kernel and its
users as it does to a desktop kernel and its users. For max
throughput, you don't want to do work in _tiny_ quantum, because you
then lose throughput due to massive cache trashing and scheduling
overhead, but latency still does matter, and not just a little.
-Mike
