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authorArjan van de Ven <arjan@linux.intel.com>2009-07-20 11:26:58 -0700
committerIngo Molnar <mingo@elte.hu>2009-09-02 08:44:08 +0200
commit8f0dfc34e9b323a028c2ec41abb7e9de477b7a94 (patch)
treefa7e44d9ad3eb22517f0724e71f9812f71a16ae2
parentf14eff1cc2f418a7c5e23aedc6a1bdca3343b871 (diff)
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>
-rw-r--r--include/linux/sched.h4
-rw-r--r--kernel/sched.c4
-rw-r--r--kernel/sched_debug.c4
-rw-r--r--kernel/sched_fair.c5
4 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e209ae0e7a8..9c96ef2f7e6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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;
diff --git a/kernel/sched.c b/kernel/sched.c
index 6244d24cafc..38d05a89e0f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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;
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 70c7e0b7994..5ddbd089126 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -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;
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 342000b31ad..471fa281f5e 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -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