Re: route cache DoS testing and softirqs

Hello!

quoted

We had one full solution for this issue not changing anything
in scheduler/softirq relationship: to run rcu task for the things
sort of dst cache not from process context, but essentially as part
of do_softirq(). Simple, stupid and apparently solves new problems
which rcu created.

Can you be a little bit more specific about this solution ?

It is about that your suggestion, which you outlined below :-)

as indicated by my earlier experiments. We have potential fixes
for RCU through a call_rcu_bh() interface where completion of a
softirq handler is a quiescent state. I am working on forward porting
that old patch from our discussion last year and testing in my
environment. That should increase the number of quiescent state
points significantly and hopefully reduce the grace period significantly.
But this does nothing to help userland starvation.

Alexey