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Commit 222d656d authored by Gautham R Shenoy's avatar Gautham R Shenoy Committed by Ingo Molnar
Browse files

sched: Define structure to store the sched_domain statistics for fbg() 



Impact: cleanup

Currently we use a lot of local variables in find_busiest_group()
to capture the various statistics related to the sched_domain.
Group them together into a single data structure.

This will help us to offload the job of updating the sched_domain
statistics to a helper function.

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: default avatarGautham R Shenoy <ego@in.ibm.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091356.13992.25970.stgit@sofia.in.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 1f8c553d

kernel/sched.c

+121 −86
Original line number Diff line number Diff line
@@ -3190,6 +3190,37 @@ static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, 
	return 0;

}

/********** Helpers for find_busiest_group ************************/

/**

 * sd_lb_stats - Structure to store the statistics of a sched_domain

 * 		during load balancing.

 */

struct sd_lb_stats {

	struct sched_group *busiest; /* Busiest group in this sd */

	struct sched_group *this;  /* Local group in this sd */

	unsigned long total_load;  /* Total load of all groups in sd */

	unsigned long total_pwr;   /*	Total power of all groups in sd */

	unsigned long avg_load;	   /* Average load across all groups in sd */



	/** Statistics of this group */

	unsigned long this_load;

	unsigned long this_load_per_task;

	unsigned long this_nr_running;



	/* Statistics of the busiest group */

	unsigned long max_load;

	unsigned long busiest_load_per_task;

	unsigned long busiest_nr_running;



	int group_imb; /* Is there imbalance in this sd */

#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)

	int power_savings_balance; /* Is powersave balance needed for this sd */

	struct sched_group *group_min; /* Least loaded group in sd */

	struct sched_group *group_leader; /* Group which relieves group_min */

	unsigned long min_load_per_task; /* load_per_task in group_min */

	unsigned long leader_nr_running; /* Nr running of group_leader */

	unsigned long min_nr_running; /* Nr running of group_min */

#endif

};



/**

 * sg_lb_stats - stats of a sched_group required for load_balancing
@@ -3346,23 +3377,16 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		   unsigned long *imbalance, enum cpu_idle_type idle,

		   int *sd_idle, const struct cpumask *cpus, int *balance)

{

	struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;

	unsigned long max_load, avg_load, total_load, this_load, total_pwr;

	struct sd_lb_stats sds;

	struct sched_group *group = sd->groups;

	unsigned long max_pull;

	unsigned long busiest_load_per_task, busiest_nr_running;

	unsigned long this_load_per_task, this_nr_running;

	int load_idx, group_imb = 0;

	int load_idx;



	memset(&sds, 0, sizeof(sds));

#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)

	int power_savings_balance = 1;

	unsigned long leader_nr_running = 0, min_load_per_task = 0;

	unsigned long min_nr_running = ULONG_MAX;

	struct sched_group *group_min = NULL, *group_leader = NULL;

	sds.power_savings_balance = 1;

	sds.min_nr_running = ULONG_MAX;

#endif



	max_load = this_load = total_load = total_pwr = 0;

	busiest_load_per_task = busiest_nr_running = 0;

	this_load_per_task = this_nr_running = 0;



	load_idx = get_sd_load_idx(sd, idle);



	do {
@@ -3378,22 +3402,22 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		if (balance && !(*balance))

			goto ret;



		total_load += sgs.group_load;

		total_pwr += group->__cpu_power;

		sds.total_load += sgs.group_load;

		sds.total_pwr += group->__cpu_power;



		if (local_group) {

			this_load = sgs.avg_load;

			this = group;

			this_nr_running = sgs.sum_nr_running;

			this_load_per_task = sgs.sum_weighted_load;

		} else if (sgs.avg_load > max_load &&

			sds.this_load = sgs.avg_load;

			sds.this = group;

			sds.this_nr_running = sgs.sum_nr_running;

			sds.this_load_per_task = sgs.sum_weighted_load;

		} else if (sgs.avg_load > sds.max_load &&

			   (sgs.sum_nr_running > sgs.group_capacity ||

				sgs.group_imb)) {

			max_load = sgs.avg_load;

			busiest = group;

			busiest_nr_running = sgs.sum_nr_running;

			busiest_load_per_task = sgs.sum_weighted_load;

			group_imb = sgs.group_imb;

			sds.max_load = sgs.avg_load;

			sds.busiest = group;

			sds.busiest_nr_running = sgs.sum_nr_running;

			sds.busiest_load_per_task = sgs.sum_weighted_load;

			sds.group_imb = sgs.group_imb;

		}



#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
@@ -3409,15 +3433,16 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		 * If the local group is idle or completely loaded

		 * no need to do power savings balance at this domain

		 */

		if (local_group && (this_nr_running >= sgs.group_capacity ||

				    !this_nr_running))

			power_savings_balance = 0;

		if (local_group &&

			(sds.this_nr_running >= sgs.group_capacity ||

			!sds.this_nr_running))

			sds.power_savings_balance = 0;



		/*

		 * If a group is already running at full capacity or idle,

		 * don't include that group in power savings calculations

		 */

		if (!power_savings_balance ||

		if (!sds.power_savings_balance ||

			sgs.sum_nr_running >= sgs.group_capacity ||

			!sgs.sum_nr_running)

			goto group_next;
@@ -3427,12 +3452,13 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		 * This is the group from where we need to pick up the load

		 * for saving power

		 */

		if ((sgs.sum_nr_running < min_nr_running) ||

		    (sgs.sum_nr_running == min_nr_running &&

		     group_first_cpu(group) > group_first_cpu(group_min))) {

			group_min = group;

			min_nr_running = sgs.sum_nr_running;

			min_load_per_task = sgs.sum_weighted_load /

		if ((sgs.sum_nr_running < sds.min_nr_running) ||

		    (sgs.sum_nr_running == sds.min_nr_running &&

		     group_first_cpu(group) >

			group_first_cpu(sds.group_min))) {

			sds.group_min = group;

			sds.min_nr_running = sgs.sum_nr_running;

			sds.min_load_per_task = sgs.sum_weighted_load /

						sgs.sum_nr_running;

		}
@@ -3444,29 +3470,32 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		if (sgs.sum_nr_running > sgs.group_capacity - 1)

			goto group_next;



		if (sgs.sum_nr_running > leader_nr_running ||

		    (sgs.sum_nr_running == leader_nr_running &&

		     group_first_cpu(group) < group_first_cpu(group_leader))) {

			group_leader = group;

			leader_nr_running = sgs.sum_nr_running;

		if (sgs.sum_nr_running > sds.leader_nr_running ||

		    (sgs.sum_nr_running == sds.leader_nr_running &&

		     group_first_cpu(group) <

			group_first_cpu(sds.group_leader))) {

			sds.group_leader = group;

			sds.leader_nr_running = sgs.sum_nr_running;

		}

group_next:

#endif

		group = group->next;

	} while (group != sd->groups);



	if (!busiest || this_load >= max_load || busiest_nr_running == 0)

	if (!sds.busiest || sds.this_load >= sds.max_load

		|| sds.busiest_nr_running == 0)

		goto out_balanced;



	avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;

	sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;



	if (this_load >= avg_load ||

			100*max_load <= sd->imbalance_pct*this_load)

	if (sds.this_load >= sds.avg_load ||

			100*sds.max_load <= sd->imbalance_pct * sds.this_load)

		goto out_balanced;



	busiest_load_per_task /= busiest_nr_running;

	if (group_imb)

		busiest_load_per_task = min(busiest_load_per_task, avg_load);

	sds.busiest_load_per_task /= sds.busiest_nr_running;

	if (sds.group_imb)

		sds.busiest_load_per_task =

			min(sds.busiest_load_per_task, sds.avg_load);



	/*

	 * We're trying to get all the cpus to the average_load, so we don't
@@ -3479,7 +3508,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
	 * by pulling tasks to us. Be careful of negative numbers as they'll

	 * appear as very large values with unsigned longs.

	 */

	if (max_load <= busiest_load_per_task)

	if (sds.max_load <= sds.busiest_load_per_task)

		goto out_balanced;



	/*
@@ -3487,17 +3516,18 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
	 * max load less than avg load(as we skip the groups at or below

	 * its cpu_power, while calculating max_load..)

	 */

	if (max_load < avg_load) {

	if (sds.max_load < sds.avg_load) {

		*imbalance = 0;

		goto small_imbalance;

	}



	/* Don't want to pull so many tasks that a group would go idle */

	max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);

	max_pull = min(sds.max_load - sds.avg_load,

			sds.max_load - sds.busiest_load_per_task);



	/* How much load to actually move to equalise the imbalance */

	*imbalance = min(max_pull * busiest->__cpu_power,

				(avg_load - this_load) * this->__cpu_power)

	*imbalance = min(max_pull * sds.busiest->__cpu_power,

			(sds.avg_load - sds.this_load) * sds.this->__cpu_power)

			/ SCHED_LOAD_SCALE;



	/*
@@ -3506,24 +3536,27 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
	 * a think about bumping its value to force at least one task to be

	 * moved

	 */

	if (*imbalance < busiest_load_per_task) {

	if (*imbalance < sds.busiest_load_per_task) {

		unsigned long tmp, pwr_now, pwr_move;

		unsigned int imbn;



small_imbalance:

		pwr_move = pwr_now = 0;

		imbn = 2;

		if (this_nr_running) {

			this_load_per_task /= this_nr_running;

			if (busiest_load_per_task > this_load_per_task)

		if (sds.this_nr_running) {

			sds.this_load_per_task /= sds.this_nr_running;

			if (sds.busiest_load_per_task >

					sds.this_load_per_task)

				imbn = 1;

		} else

			this_load_per_task = cpu_avg_load_per_task(this_cpu);

			sds.this_load_per_task =

				cpu_avg_load_per_task(this_cpu);



		if (max_load - this_load + busiest_load_per_task >=

					busiest_load_per_task * imbn) {

			*imbalance = busiest_load_per_task;

			return busiest;

		if (sds.max_load - sds.this_load +

			sds.busiest_load_per_task >=

				sds.busiest_load_per_task * imbn) {

			*imbalance = sds.busiest_load_per_task;

			return sds.busiest;

		}



		/*
@@ -3532,52 +3565,54 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, 
		 * moving them.

		 */



		pwr_now += busiest->__cpu_power *

				min(busiest_load_per_task, max_load);

		pwr_now += this->__cpu_power *

				min(this_load_per_task, this_load);

		pwr_now += sds.busiest->__cpu_power *

				min(sds.busiest_load_per_task, sds.max_load);

		pwr_now += sds.this->__cpu_power *

				min(sds.this_load_per_task, sds.this_load);

		pwr_now /= SCHED_LOAD_SCALE;



		/* Amount of load we'd subtract */

		tmp = sg_div_cpu_power(busiest,

				busiest_load_per_task * SCHED_LOAD_SCALE);

		if (max_load > tmp)

			pwr_move += busiest->__cpu_power *

				min(busiest_load_per_task, max_load - tmp);

		tmp = sg_div_cpu_power(sds.busiest,

				sds.busiest_load_per_task * SCHED_LOAD_SCALE);

		if (sds.max_load > tmp)

			pwr_move += sds.busiest->__cpu_power *

				min(sds.busiest_load_per_task,

						sds.max_load - tmp);



		/* Amount of load we'd add */

		if (max_load * busiest->__cpu_power <

				busiest_load_per_task * SCHED_LOAD_SCALE)

			tmp = sg_div_cpu_power(this,

					max_load * busiest->__cpu_power);

		if (sds.max_load * sds.busiest->__cpu_power <

				sds.busiest_load_per_task * SCHED_LOAD_SCALE)

			tmp = sg_div_cpu_power(sds.this,

				sds.max_load * sds.busiest->__cpu_power);

		else

			tmp = sg_div_cpu_power(this,

				busiest_load_per_task * SCHED_LOAD_SCALE);

		pwr_move += this->__cpu_power *

				min(this_load_per_task, this_load + tmp);

			tmp = sg_div_cpu_power(sds.this,

				sds.busiest_load_per_task * SCHED_LOAD_SCALE);

		pwr_move += sds.this->__cpu_power *

				min(sds.this_load_per_task,

					sds.this_load + tmp);

		pwr_move /= SCHED_LOAD_SCALE;



		/* Move if we gain throughput */

		if (pwr_move > pwr_now)

			*imbalance = busiest_load_per_task;

			*imbalance = sds.busiest_load_per_task;

	}



	return busiest;

	return sds.busiest;



out_balanced:

#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)

	if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))

		goto ret;



	if (this != group_leader || group_leader == group_min)

	if (sds.this != sds.group_leader || sds.group_leader == sds.group_min)

		goto ret;



	*imbalance = min_load_per_task;

	*imbalance = sds.min_load_per_task;

	if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {

		cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =

			group_first_cpu(group_leader);

			group_first_cpu(sds.group_leader);

	}

	return group_min;

	return sds.group_min;



#endif

ret: