[PATCH 5/6] psi: rename psi fields in preparation for psi trigger addition

Suren Baghdasaryan
2018-12-14T17:16:30Z

Renaming psi_group structure member fields used for calculating psi
totals and averages for clear distinction between them and trigger-related
fields that will be added next.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
include/linux/psi_types.h | 15 ++++++++-------
kernel/sched/psi.c | 26 ++++++++++++++------------
2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
index 2c6e9b67b7eb..11b32b3395a2 100644
--- a/include/linux/psi_types.h
+++ b/include/linux/psi_types.h
@@ -69,20 +69,21 @@ struct psi_group_cpu {
};

struct psi_group {
- /* Protects data updated during an aggregation */
- struct mutex stat_lock;
+ /* Protects data used by the aggregator */
+ struct mutex update_lock;

/* Per-cpu task state & time tracking */
struct psi_group_cpu __percpu *pcpu;

- /* Periodic aggregation state */
- u64 total_prev[NR_PSI_STATES - 1];
- u64 last_update;
- u64 next_update;
struct delayed_work clock_work;

- /* Total stall times and sampled pressure averages */
+ /* Total stall times observed */
u64 total[NR_PSI_STATES - 1];
+
+ /* Running pressure averages */
+ u64 avg_total[NR_PSI_STATES - 1];
+ u64 avg_last_update;
+ u64 avg_next_update;
unsigned long avg[NR_PSI_STATES - 1][3];
};

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 153c0624976b..694edefdd333 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -172,9 +172,9 @@ static void group_init(struct psi_group *group)

for_each_possible_cpu(cpu)
seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
- group->next_update = sched_clock() + psi_period;
+ group->avg_next_update = sched_clock() + psi_period;
INIT_DELAYED_WORK(&group->clock_work, psi_update_work);
- mutex_init(&group->stat_lock);
+ mutex_init(&group->update_lock);
}

void __init psi_init(void)
@@ -268,7 +268,7 @@ static void update_stats(struct psi_group *group)
int cpu;
int s;

- mutex_lock(&group->stat_lock);
+ mutex_lock(&group->update_lock);

/*
* Collect the per-cpu time buckets and average them into a
@@ -309,7 +309,7 @@ static void update_stats(struct psi_group *group)

/* avgX= */
now = sched_clock();
- expires = group->next_update;
+ expires = group->avg_next_update;
if (now < expires)
goto out;

@@ -320,14 +320,14 @@ static void update_stats(struct psi_group *group)
* But the deltas we sample out of the per-cpu buckets above
* are based on the actual time elapsing between clock ticks.
*/
- group->next_update = expires + psi_period;
- period = now - group->last_update;
- group->last_update = now;
+ group->avg_next_update = expires + psi_period;
+ period = now - group->avg_last_update;
+ group->avg_last_update = now;

for (s = 0; s < NR_PSI_STATES - 1; s++) {
u32 sample;

- sample = group->total[s] - group->total_prev[s];
+ sample = group->total[s] - group->avg_total[s];
/*
* Due to the lockless sampling of the time buckets,
* recorded time deltas can slip into the next period,
@@ -347,11 +347,11 @@ static void update_stats(struct psi_group *group)
*/
if (sample > period)
sample = period;
- group->total_prev[s] += sample;
+ group->avg_total[s] += sample;
calc_avgs(group->avg[s], sample, period);
}
out:
- mutex_unlock(&group->stat_lock);
+ mutex_unlock(&group->update_lock);
}

static void psi_update_work(struct work_struct *work)
@@ -375,8 +375,10 @@ static void psi_update_work(struct work_struct *work)
update_stats(group);

now = sched_clock();
- if (group->next_update > now)
- delay = nsecs_to_jiffies(group->next_update - now) + 1;
+ if (group->avg_next_update > now) {
+ delay = nsecs_to_jiffies(
+ group->avg_next_update - now) + 1;
+ }
schedule_delayed_work(dwork, delay);
}

--
2.20.0.405.gbc1bbc6f85-goog