Messages in this thread | | | From | "Zhang, Qiang1" <> | Subject | RE: [PATCH] rcu: Remove duplicate settings for rcu boost kthreads affinity | Date | Sat, 17 Dec 2022 02:00:35 +0000 |
| |
On Thu, Dec 15, 2022 at 05:00:29PM +0800, Zqiang wrote: > Currently, when CPUs going offline, the rcu boost kthreads CPU > affinity has been reset in rcutree_offline_cpu(), therefore this > commit remove duplicate settings in rcutree_dead_cpu(). > > Signed-off-by: Zqiang <qiang1.zhang@intel.com> > >One question... > >Given that rcutree_offline_cpu() causes rcu_boost_kthread_setaffinity() >to be invoked with the number of the outgoing CPU, but rcutree_dead_cpu() >instead passes in -1, are these two invocations really redundant?
Although -1 is passed in, but at this time, the outgoing CPU has been removed from rcu_rnp_online_cpus(rnp), in other words, we will eliminate the same CPU, which is also we passed in cpu in the rcutree_offline_cpu() before.
Thanks Zqiang
> > Thanx, paul
> --- > kernel/rcu/tree.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 65f3dd2fd3ae..20de83ed0c7e 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4122,15 +4122,10 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf) > */ > int rcutree_dead_cpu(unsigned int cpu) > { > - struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); > - struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ > - > if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) > return 0; > > WRITE_ONCE(rcu_state.n_online_cpus, rcu_state.n_online_cpus - 1); > - /* Adjust any no-longer-needed kthreads. */ > - rcu_boost_kthread_setaffinity(rnp, -1); > // Stop-machine done, so allow nohz_full to disable tick. > tick_dep_clear(TICK_DEP_BIT_RCU); > return 0; > -- > 2.25.1 >
| |