Re: [PATCH tip/core/rcu 0/21] Contention reduction for v4.18

[Paul E. McKenney]

On Mon, May 14, 2018 at 04:42:33PM +1000, Nicholas Piggin wrote:
> On Sun, 22 Apr 2018 20:02:58 -0700
> "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > Hello!
> > 
> > This series reduces lock contention on the root rcu_node structure,
> > and is also the first precursor to TBD changes to consolidate the
> > three RCU flavors (RCU-bh, RCU-preempt, and RCU-sched) into one.
> 
> Hi Paul,
> 
> I've been running your rcu/dev branch and haven't noticed any problems
> yet. The irqsoff latency improvement is a little hard to measure
> because the scheduler, but I've tried turning balancing parameters
> right down and I'm yet to see any sign of RCU in traces (down to about
> 100us on a 176 CPU machine), so that's great.

Good to hear!!!

> (Not that RCU was ever the worst contributor to latency as I said, just
> that I noticed those couple of traces where it showed up.)
> 
> Thanks very much for the fast response, sorry I've taken a while to
> test.

Would you be willing to give me a Tested-by on that series of patches?

							Thanx, Paul