From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Yunfeng Ye <yeyunfeng@huawei.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH 6/8] tick/nohz: Only wakeup a single target cpu when kicking a task
Date: Mon, 10 May 2021 12:54:00 +0200 [thread overview]
Message-ID: <20210510105400.GC97481@lothringen> (raw)
In-Reply-To: <YJkPbkMiteUCYFru@hirez.programming.kicks-ass.net>
On Mon, May 10, 2021 at 12:48:14PM +0200, Peter Zijlstra wrote:
> On Mon, May 10, 2021 at 12:39:01PM +0200, Frederic Weisbecker wrote:
> > On Wed, May 05, 2021 at 03:43:28PM +0200, Peter Zijlstra wrote:
> > > That had me looking at tick_nohz_task_switch(), does we want the below?
> > >
> > >
> > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > > index 9143163fa678..ff45fc513ba7 100644
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -4207,6 +4207,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
> > > vtime_task_switch(prev);
> > > perf_event_task_sched_in(prev, current);
> > > finish_task(prev);
> > > + tick_nohz_task_switch();
> > > finish_lock_switch(rq);
> > > finish_arch_post_lock_switch();
> > > kcov_finish_switch(current);
> > > @@ -4252,7 +4253,6 @@ static struct rq *finish_task_switch(struct task_struct *prev)
> > > put_task_struct_rcu_user(prev);
> > > }
> > >
> > > - tick_nohz_task_switch();
> > > return rq;
> > > }
> > >
> > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> > > index 828b091501ca..ea079be9097f 100644
> > > --- a/kernel/time/tick-sched.c
> > > +++ b/kernel/time/tick-sched.c
> > > @@ -447,13 +447,10 @@ void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bi
> > > */
> > > void __tick_nohz_task_switch(void)
> > > {
> > > - unsigned long flags;
> > > struct tick_sched *ts;
> > >
> > > - local_irq_save(flags);
> > > -
> > > if (!tick_nohz_full_cpu(smp_processor_id()))
> > > - goto out;
> > > + return;
> > >
> > > ts = this_cpu_ptr(&tick_cpu_sched);
> > >
> > > @@ -462,8 +459,6 @@ void __tick_nohz_task_switch(void)
> > > atomic_read(¤t->signal->tick_dep_mask))
> > > tick_nohz_full_kick();
> > > }
> > > -out:
> > > - local_irq_restore(flags);
> > > }
> > >
> > > /* Get the boot-time nohz CPU list from the kernel parameters. */
> >
> >
> > Sure, I'll take your SoB on that too, ok?
>
> OK, but please also test it :-) I didn't even ask a compiler it's
> opinion on the thing.
Of course, there will be another version of the patchset + usual testing :-)
next prev parent reply other threads:[~2021-05-10 11:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 12:01 [PATCH 0/8] tick/nohz updates v2 Frederic Weisbecker
2021-04-22 12:01 ` [PATCH 1/8] tick/nohz: Evaluate the CPU expression after the static key Frederic Weisbecker
2021-05-04 12:31 ` Peter Zijlstra
2021-04-22 12:01 ` [PATCH 2/8] tick/nohz: Conditionally restart tick on idle exit Frederic Weisbecker
2021-04-22 12:01 ` [PATCH 3/8] tick/nohz: Remove superflous check for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE Frederic Weisbecker
2021-05-04 12:40 ` Peter Zijlstra
2021-04-22 12:01 ` [PATCH 4/8] tick/nohz: Update idle_exittime on actual idle exit Frederic Weisbecker
2021-04-22 12:01 ` [PATCH 5/8] tick/nohz: Update nohz_full Kconfig help Frederic Weisbecker
2021-04-22 12:01 ` [PATCH 6/8] tick/nohz: Only wakeup a single target cpu when kicking a task Frederic Weisbecker
2021-05-05 13:43 ` Peter Zijlstra
2021-05-10 10:39 ` Frederic Weisbecker
2021-05-10 10:48 ` Peter Zijlstra
2021-05-10 10:54 ` Frederic Weisbecker [this message]
2021-04-22 12:01 ` [PATCH 7/8] tick/nohz: Change signal tick dependency to wakeup CPUs of member tasks Frederic Weisbecker
2021-04-22 12:01 ` [PATCH 8/8] tick/nohz: Kick only _queued_ task whose tick dependency is updated Frederic Weisbecker
2021-05-05 13:57 ` Peter Zijlstra
2021-05-10 10:52 ` Frederic Weisbecker
2021-05-05 13:57 ` [PATCH 0/8] tick/nohz updates v2 Peter Zijlstra
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