Hello Daniel, > -----Original Message----- > From: Daniel Lezcano [mailto:[email protected]] > Sent: Thursday, August 21, 2014 9:54 AM > To: Liu, Chuansheng; [email protected]; [email protected]; > [email protected]; [email protected] > Cc: [email protected]; [email protected]; Liu, Changcheng; > Wang, Xiaoming; Chakravarty, Souvik K > Subject: Re: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the > idle cpu > > On 08/18/2014 10:37 AM, Chuansheng Liu wrote: > > Implementing one new API wake_up_if_idle(), which is used to > > wake up the idle CPU. > > Is this patchset tested ? Did you check it solves the issue you were > facing ? We have done the basic test, and found the cores can exit C0 quickly with this patchset. Basically once the _TIF_NEED_RESCHED is set, then the poll_idle() can be broken.
Please correct me if something is wrong, thanks. > > > Suggested-by: Andy Lutomirski <[email protected]> > > Signed-off-by: Chuansheng Liu <[email protected]> > > --- > > include/linux/sched.h | 1 + > > kernel/sched/core.c | 16 ++++++++++++++++ > > 2 files changed, 17 insertions(+) > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 857ba40..3f89ac1 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 1211575..adf104f 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -1620,6 +1620,22 @@ 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 (set_nr_if_polling(rq->idle)) { > > + trace_sched_wake_idle_without_ipi(cpu); > > + } else { > > + raw_spin_lock_irqsave(&rq->lock, flags); > > + if (rq->curr == rq->idle) > > + 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); > > > > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM > SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog
