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

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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: Swapnil Sapkal <swapnil.sapkal@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20241220063224.17767-4-swapnil.sapkal@amd.com
This commit is contained in:
Swapnil Sapkal 2024-12-20 06:32:21 +00:00 committed by Peter Zijlstra
parent c3856c9ce6
commit 3b2a793ea7
3 changed files with 32 additions and 4 deletions
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5
include/linux/sched/topology.h
View File

@ -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];

24
kernel/sched/fair.c
View File

@ -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 @@ redo:
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;

7
kernel/sched/stats.c
View File

@ -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],