Messages in this thread | | | From | Andy Lutomirski <> | Date | Fri, 19 Dec 2014 12:23:16 -0800 | Subject | Re: [tip:sched/core] sched: Add new API wake_up_if_idle() to wake up the idle cpu |
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On Fri, Sep 19, 2014 at 4:43 AM, tip-bot for Chuansheng Liu <tipbot@zytor.com> wrote: > Commit-ID: f6be8af1c95de4a46e325e728900a70ceadb52cf > Gitweb: http://git.kernel.org/tip/f6be8af1c95de4a46e325e728900a70ceadb52cf > Author: Chuansheng Liu <chuansheng.liu@intel.com> > AuthorDate: Thu, 4 Sep 2014 15:17:53 +0800 > Committer: Ingo Molnar <mingo@kernel.org> > CommitDate: Fri, 19 Sep 2014 12:35:14 +0200 > > sched: Add new API wake_up_if_idle() to wake up the idle cpu > > Implementing one new API wake_up_if_idle(), which is used to > wake up the idle CPU. > > Suggested-by: Andy Lutomirski <luto@amacapital.net> > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: daniel.lezcano@linaro.org > Cc: rjw@rjwysocki.net > Cc: linux-pm@vger.kernel.org > Cc: changcheng.liu@intel.com > Cc: xiaoming.wang@intel.com > Cc: souvik.k.chakravarty@intel.com > Cc: chuansheng.liu@intel.com > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Link: http://lkml.kernel.org/r/1409815075-4180-1-git-send-email-chuansheng.liu@intel.com > Signed-off-by: Ingo Molnar <mingo@kernel.org> > --- > include/linux/sched.h | 1 + > kernel/sched/core.c | 19 +++++++++++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index dd9eb48..82ff3d6 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1024,6 +1024,7 @@ struct sched_domain_topology_level { > extern struct sched_domain_topology_level *sched_domain_topology; > > extern void set_sched_topology(struct sched_domain_topology_level *tl); > +extern void wake_up_if_idle(int cpu); > > #ifdef CONFIG_SCHED_DEBUG > # define SD_INIT_NAME(type) .name = #type > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 78e5c83..f7c6ed2 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1634,6 +1634,25 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu) > } > } > > +void wake_up_if_idle(int cpu) > +{ > + struct rq *rq = cpu_rq(cpu); > + unsigned long flags; > + > + if (!is_idle_task(rq->curr))
This is old news, but why isn't this if (rq->curr != rq->idle)?
--Andy
> + return; > + > + if (set_nr_if_polling(rq->idle)) { > + trace_sched_wake_idle_without_ipi(cpu); > + } else { > + raw_spin_lock_irqsave(&rq->lock, flags); > + if (is_idle_task(rq->curr)) > + smp_send_reschedule(cpu); > + /* Else cpu is not in idle, do nothing here */ > + raw_spin_unlock_irqrestore(&rq->lock, flags); > + } > +} > + > bool cpus_share_cache(int this_cpu, int that_cpu) > { > return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
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