Commit 847fc0cd authored by Yafang Shao's avatar Yafang Shao Committed by Peter Zijlstra
Browse files

sched: Introduce task block time in schedstats 



Currently in schedstats we have sum_sleep_runtime and iowait_sum, but
there's no metric to show how long the task is in D state.  Once a task in
D state, it means the task is blocked in the kernel, for example the
task may be waiting for a mutex. The D state is more frequent than
iowait, and it is more critital than S state. So it is worth to add a
metric to measure it.

Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210905143547.4668-5-laoar.shao@gmail.com
parent 60f2415e

include/linux/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -503,6 +503,8 @@ struct sched_statistics { 


	u64				block_start;

	u64				block_max;

	s64				sum_block_runtime;



	u64				exec_max;

	u64				slice_max;

kernel/sched/debug.c

+4 −2
Original line number Diff line number Diff line
@@ -540,10 +540,11 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p) 
		(long long)(p->nvcsw + p->nivcsw),

		p->prio);



	SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",

	SEQ_printf(m, "%9lld.%06ld %9lld.%06ld %9lld.%06ld %9lld.%06ld",

		SPLIT_NS(schedstat_val_or_zero(p->stats.wait_sum)),

		SPLIT_NS(p->se.sum_exec_runtime),

		SPLIT_NS(schedstat_val_or_zero(p->stats.sum_sleep_runtime)));

		SPLIT_NS(schedstat_val_or_zero(p->stats.sum_sleep_runtime)),

		SPLIT_NS(schedstat_val_or_zero(p->stats.sum_block_runtime)));



#ifdef CONFIG_NUMA_BALANCING

	SEQ_printf(m, " %d %d", task_node(p), task_numa_group_id(p));
@@ -977,6 +978,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns, 
		u64 avg_atom, avg_per_cpu;



		PN_SCHEDSTAT(sum_sleep_runtime);

		PN_SCHEDSTAT(sum_block_runtime);

		PN_SCHEDSTAT(wait_start);

		PN_SCHEDSTAT(sleep_start);

		PN_SCHEDSTAT(block_start);

kernel/sched/stats.c

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ void __update_stats_enqueue_sleeper(struct rq *rq, struct task_struct *p, 


		__schedstat_set(stats->block_start, 0);

		__schedstat_add(stats->sum_sleep_runtime, delta);

		__schedstat_add(stats->sum_block_runtime, delta);



		if (p) {

			if (p->in_iowait) {