Commit c6f4459f authored Sep 04, 2014 by Chuansheng Liu Committed by Ingo Molnar Sep 19, 2014

smp: Add new wake_up_all_idle_cpus() function



Currently kick_all_cpus_sync() can break non-polling idle cpus
thru IPI interrupts.

But sometimes we need to break the polling idle cpus immediately
to reselect the suitable c-state, also for non-idle cpus, we need
to do nothing if we try to wake up them.

Here adding one new function wake_up_all_idle_cpus() to let all cpus
out of idle based on function wake_up_if_idle().

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: luto@amacapital.net
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1409815075-4180-2-git-send-email-chuansheng.liu@intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent f6be8af1

include/linux/smp.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -100,6 +100,7 @@ int smp_call_function_any(const struct cpumask *mask,
		smp_call_func_t func, void *info, int wait);

		void kick_all_cpus_sync(void);
		void wake_up_all_idle_cpus(void);

		/*
		* Generic and arch helpers
		@@ -148,6 +149,7 @@ smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
		}

		static inline void kick_all_cpus_sync(void) { }
		static inline void wake_up_all_idle_cpus(void) { }

		#endif /* !SMP */

kernel/smp.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@
		#include <linux/gfp.h>
		#include <linux/smp.h>
		#include <linux/cpu.h>
		#include <linux/sched.h>

		#include "smpboot.h"

		@@ -699,3 +700,24 @@ void kick_all_cpus_sync(void)
		smp_call_function(do_nothing, NULL, 1);
		}
		EXPORT_SYMBOL_GPL(kick_all_cpus_sync);

		/**
		* wake_up_all_idle_cpus - break all cpus out of idle
		* wake_up_all_idle_cpus try to break all cpus which is in idle state even
		* including idle polling cpus, for non-idle cpus, we will do nothing
		* for them.
		*/
		void wake_up_all_idle_cpus(void)
		{
		int cpu;

		preempt_disable();
		for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
		continue;

		wake_up_if_idle(cpu);
		}
		preempt_enable();
		}
		EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);

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