| Date | Sun, 15 Jan 2017 23:58:07 -0800 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/rcu 08/20] rcu: Add long-term CPU kicking |
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On Sat, Jan 14, 2017 at 01:13:09AM -0800, Paul E. McKenney wrote: > Commit d2db185bfee8 ("rcu: Remove short-term CPU kicking") removed > frequent calls to resched_cpu(), which means that the only time > resched_cpu() is invoked is after an RCU CPU stall warning. Although > this is good from an avoid-IPIs perspective, we should try to break > things loose -before- splatting. This commit therefore starts invoking > resched_cpu() for each holdout at each force-quiescent-state interval > that is more than halfway through the stall-warning interval. > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Could you please reverse the order of patches 7 and 8, so that unnecessary splats don't occur between the two?
For the patch itself: Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> kernel/rcu/tree.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 3c0d6c129718..5a4aaad75e76 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1220,6 +1220,13 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, > rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */ > } > > + /* > + * If more than halfway to RCU CPU stall-warning time, do > + * a resched_cpu() to try to loosen things up a bit. > + */ > + if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2) > + resched_cpu(rdp->cpu); > + > return 0; > } > > -- > 2.5.2 >
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