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sched: Provide iowait counters 

For counting how long an application has been waiting for
(disk) IO, there currently is only the HZ sample driven
information available, while for all other counters in this
class, a high resolution version is available via
CONFIG_SCHEDSTATS.

In order to make an improved bootchart tool possible, we also
need a higher resolution version of the iowait time.

This patch below adds this scheduler statistic to the kernel.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4A64B813.1080506@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven 2009-07-20 11:26:58 -07:00 committed by Ingo Molnar
parent f14eff1cc2
commit 8f0dfc34e9
4 changed files with 17 additions and 0 deletions
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4
include/linux/sched.h
View File

@ -1111,6 +1111,8 @@ struct sched_entity {
u64 wait_max;
u64 wait_count;
u64 wait_sum;
u64 iowait_count;
u64 iowait_sum;
u64 sleep_start;
u64 sleep_max;
@ -1231,6 +1233,8 @@ struct task_struct {
unsigned did_exec:1;
unsigned in_execve:1; /* Tell the LSMs that the process is doing an
* execve */
unsigned in_iowait:1;
/* Revert to default priority/policy when forking */
unsigned sched_reset_on_fork:1;

4
kernel/sched.c
View File

@ -6754,7 +6754,9 @@ void __sched io_schedule(void)
delayacct_blkio_start();
atomic_inc(&rq->nr_iowait);
current->in_iowait = 1;
schedule();
current->in_iowait = 0;
atomic_dec(&rq->nr_iowait);
delayacct_blkio_end();
}
@ -6767,7 +6769,9 @@ long __sched io_schedule_timeout(long timeout)
delayacct_blkio_start();
atomic_inc(&rq->nr_iowait);
current->in_iowait = 1;
ret = schedule_timeout(timeout);
current->in_iowait = 0;
atomic_dec(&rq->nr_iowait);
delayacct_blkio_end();
return ret;

4
kernel/sched_debug.c
View File

@ -409,6 +409,8 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
PN(se.wait_max);
PN(se.wait_sum);
P(se.wait_count);
PN(se.iowait_sum);
P(se.iowait_count);
P(sched_info.bkl_count);
P(se.nr_migrations);
P(se.nr_migrations_cold);
@ -479,6 +481,8 @@ void proc_sched_set_task(struct task_struct *p)
p->se.wait_max = 0;
p->se.wait_sum = 0;
p->se.wait_count = 0;
p->se.iowait_sum = 0;
p->se.iowait_count = 0;
p->se.sleep_max = 0;
p->se.sum_sleep_runtime = 0;
p->se.block_max = 0;

5
kernel/sched_fair.c
View File

@ -652,6 +652,11 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->sum_sleep_runtime += delta;
if (tsk) {
if (tsk->in_iowait) {
se->iowait_sum += delta;
se->iowait_count++;
}
/*
* Blocking time is in units of nanosecs, so shift by
* 20 to get a milliseconds-range estimation of the