Commit 3b2a793e authored by Swapnil Sapkal's avatar Swapnil Sapkal Committed by Peter Zijlstra
Browse files

sched: Report the different kinds of imbalances in /proc/schedstat 



In /proc/schedstat, lb_imbalance reports the sum of imbalances
discovered in sched domains with each call to sched_balance_rq(), which is
not very useful because lb_imbalance does not mention whether the imbalance
is due to load, utilization, nr_tasks or misfit_tasks. Remove this field
from /proc/schedstat.

Currently there is no field in /proc/schedstat to report different types
of imbalances. Introduce new fields in /proc/schedstat to report the
total imbalances in load, utilization, nr_tasks or misfit_tasks.

Added fields to /proc/schedstat:
        - lb_imbalance_load: Total imbalance due to load.
        - lb_imbalance_util: Total imbalance due to utilization.
        - lb_imbalance_task: Total imbalance due to number of tasks.
        - lb_imbalance_misfit: Total imbalance due to misfit tasks.

Signed-off-by: default avatarSwapnil Sapkal <swapnil.sapkal@amd.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarShrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20241220063224.17767-4-swapnil.sapkal@amd.com
parent c3856c9c

include/linux/sched/topology.h

+4 −1
Original line number Diff line number Diff line
@@ -114,7 +114,10 @@ struct sched_domain { 
	unsigned int lb_count[CPU_MAX_IDLE_TYPES];

	unsigned int lb_failed[CPU_MAX_IDLE_TYPES];

	unsigned int lb_balanced[CPU_MAX_IDLE_TYPES];

	unsigned int lb_imbalance[CPU_MAX_IDLE_TYPES];

	unsigned int lb_imbalance_load[CPU_MAX_IDLE_TYPES];

	unsigned int lb_imbalance_util[CPU_MAX_IDLE_TYPES];

	unsigned int lb_imbalance_task[CPU_MAX_IDLE_TYPES];

	unsigned int lb_imbalance_misfit[CPU_MAX_IDLE_TYPES];

	unsigned int lb_gained[CPU_MAX_IDLE_TYPES];

	unsigned int lb_hot_gained[CPU_MAX_IDLE_TYPES];

	unsigned int lb_nobusyg[CPU_MAX_IDLE_TYPES];

kernel/sched/fair.c

+23 −1
Original line number Diff line number Diff line
@@ -11705,6 +11705,28 @@ static int should_we_balance(struct lb_env *env) 
	return group_balance_cpu(sg) == env->dst_cpu;

}



static void update_lb_imbalance_stat(struct lb_env *env, struct sched_domain *sd,

				     enum cpu_idle_type idle)

{

	if (!schedstat_enabled())

		return;



	switch (env->migration_type) {

	case migrate_load:

		__schedstat_add(sd->lb_imbalance_load[idle], env->imbalance);

		break;

	case migrate_util:

		__schedstat_add(sd->lb_imbalance_util[idle], env->imbalance);

		break;

	case migrate_task:

		__schedstat_add(sd->lb_imbalance_task[idle], env->imbalance);

		break;

	case migrate_misfit:

		__schedstat_add(sd->lb_imbalance_misfit[idle], env->imbalance);

		break;

	}

}



/*

 * Check this_cpu to ensure it is balanced within domain. Attempt to move

 * tasks if there is an imbalance.
@@ -11755,7 +11777,7 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, 


	WARN_ON_ONCE(busiest == env.dst_rq);



	schedstat_add(sd->lb_imbalance[idle], env.imbalance);

	update_lb_imbalance_stat(&env, sd, idle);



	env.src_cpu = busiest->cpu;

	env.src_rq = busiest;

kernel/sched/stats.c

+5 −2
Original line number Diff line number Diff line
@@ -141,11 +141,14 @@ static int show_schedstat(struct seq_file *seq, void *v) 
			seq_printf(seq, "domain%d %*pb", dcount++,

				   cpumask_pr_args(sched_domain_span(sd)));

			for (itype = 0; itype < CPU_MAX_IDLE_TYPES; itype++) {

				seq_printf(seq, " %u %u %u %u %u %u %u %u",

				seq_printf(seq, " %u %u %u %u %u %u %u %u %u %u %u",

				    sd->lb_count[itype],

				    sd->lb_balanced[itype],

				    sd->lb_failed[itype],

				    sd->lb_imbalance[itype],

				    sd->lb_imbalance_load[itype],

				    sd->lb_imbalance_util[itype],

				    sd->lb_imbalance_task[itype],

				    sd->lb_imbalance_misfit[itype],

				    sd->lb_gained[itype],

				    sd->lb_hot_gained[itype],

				    sd->lb_nobusyq[itype],