Messages in this thread | | | Date | Thu, 21 Aug 2014 05:48:11 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the idle cpu |
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On 08/21/2014 04:12 AM, Liu, Chuansheng wrote: > Hello Daniel, > >> -----Original Message----- >> From: Daniel Lezcano [mailto:daniel.lezcano@linaro.org] >> Sent: Thursday, August 21, 2014 9:54 AM >> To: Liu, Chuansheng; luto@amacapital.net; peterz@infradead.org; >> rjw@rjwysocki.net; mingo@redhat.com >> Cc: linux-pm@vger.kernel.org; linux-kernel@vger.kernel.org; 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.
Actually, it was not clear for me if this patch was a proposal or not.
I will review it.
Thanks
-- Daniel
>>> Suggested-by: Andy Lutomirski <luto@amacapital.net> >>> Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com> >>> --- >>> 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 >
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