Re: [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks for RCU

[Paul E. McKenney]

On Mon, Jun 23, 2014 at 05:20:30PM -0700, Dave Hansen wrote:
> On 06/23/2014 05:15 PM, Paul E. McKenney wrote:
> > Just out of curiosity, how many CPUs does your system have?  80?
> > If 160, looks like something bad is happening at 80.
> 
> 80 cores, 160 threads.  >80 processes/threads is where we start using
> the second thread on the cores.  The tasks are also pinned to
> hyperthread pairs, so they disturb each other, and the scheduler moves
> them between threads on occasion which causes extra noise.

OK, that could explain the near flattening of throughput near 80
processes.  Is 3.16.0-rc1-pf2 with the two RCU patches?  If so, is the
new sysfs parameter at its default value?

							Thanx, Paul

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/