Commit 11bd67db authored by Andy Ross's avatar Andy Ross Committed by Anas Nashif
Browse files

kernel/idle: Use normal idle in SMP when IPI is available 



Now that we have a working IPI framework, there's no reason for the
default spin loop for the SMP idle thread.  Just use the default
platform idle and send an IPI when a new thread is readied.

Long term, this can be optimized if necessary (e.g. only send the IPI
to idling CPUs, or check priorities, etc...), but for a 2-cpu system
this is a very reasonable default.

Signed-off-by: default avatarAndy Ross <andrew.j.ross@intel.com>
parent 6c283ca3

kernel/idle.c

+7 −9
Original line number Diff line number Diff line
@@ -19,6 +19,10 @@ 
#define IDLE_THRESH 1

#endif



/* Fallback idle spin loop for SMP platforms without a working IPI */

#define SMP_FALLBACK \

	(defined(CONFIG_SMP) && !defined(CONFIG_SCHED_IPI_SUPPORTED))



#ifdef CONFIG_SYS_POWER_MANAGEMENT

/*

 * Used to allow _sys_suspend() implementation to control notification
@@ -56,7 +60,7 @@ void __attribute__((weak)) _sys_resume_from_deep_sleep(void) 
 *

 * @return N/A

 */

#ifndef CONFIG_SMP

#if !SMP_FALLBACK

static void set_kernel_idle_time_in_ticks(s32_t ticks)

{

#ifdef CONFIG_SYS_POWER_MANAGEMENT
@@ -145,18 +149,12 @@ void idle(void *unused1, void *unused2, void *unused3) 
	__idle_time_stamp = k_cycle_get_32();

#endif



#ifdef CONFIG_SMP

	/* Simplified idle for SMP CPUs pending driver support.  The

	 * busy waiting is needed to prevent lock contention.  Long

	 * term we need to wake up idle CPUs with an IPI.

	 */

	while (true) {

#if SMP_FALLBACK

		k_busy_wait(100);

		k_yield();

	}

#else

	for (;;) {

		(void)irq_lock();

		(void)z_arch_irq_lock();

		sys_power_save_idle();



		IDLE_YIELD_IF_COOP();

kernel/sched.c

+3 −0
Original line number Diff line number Diff line
@@ -336,6 +336,9 @@ void z_add_thread_to_ready_q(struct k_thread *thread) 
		_priq_run_add(&_kernel.ready_q.runq, thread);

		z_mark_thread_as_queued(thread);

		update_cache(0);

#ifdef CONFIG_SCHED_IPI_SUPPORTED

		z_arch_sched_ipi();

#endif

	}

}

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