Messages in this thread | | | Date | Sat, 21 Jan 2017 12:42:55 -0800 | From | Josh Triplett <> | Subject | Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking |
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On Tue, Jan 17, 2017 at 06:53:46PM -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.
Just realized an issue with this commit message: you're referring to what now appears as patch 8 in the past tense as something already done, and with a commit ID that probably doesn't work anymore. You need to rephrase this to describe how it leads to a *subsequent* change rather than fixing something already changed.
With the commit message fixed: Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> --- > kernel/rcu/tree.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 83bf054e194e..0e61b62e3f4a 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1225,6 +1225,12 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, > rdp->rsp->gp_start + 2 * jiffies_till_sched_qs) || > ULONG_CMP_GE(jiffies, rdp->rsp->gp_start + jiffies_till_sched_qs)) > resched_cpu(rdp->cpu); /* Force CPU into scheduler. */ > + /* > + * 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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