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Subject[PATCH 5/8] PM: suspend_block: Add suspend_blocker stats
Date
Report suspend block stats in /sys/kernel/debug/suspend_blockers.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
include/linux/suspend_blocker.h | 27 +++++-
kernel/power/Kconfig | 8 ++
kernel/power/opportunistic_suspend.c | 195 +++++++++++++++++++++++++++++++++-
kernel/power/power.h | 5 +
kernel/power/suspend.c | 4 +-
5 files changed, 235 insertions(+), 4 deletions(-)

diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.h
index 8788302..256af15 100755
--- a/include/linux/suspend_blocker.h
+++ b/include/linux/suspend_blocker.h
@@ -17,11 +17,35 @@
#define _LINUX_SUSPEND_BLOCKER_H

#include <linux/list.h>
+#include <linux/ktime.h>
+
+/**
+ * struct suspend_blocker_stats - statistics for a suspend blocker
+ *
+ * @count: Number of times this blocker has been deacivated.
+ * @wakeup_count: Number of times this blocker was the first to block suspend
+ * after resume.
+ * @total_time: Total time this suspend blocker has prevented suspend.
+ * @prevent_suspend_time: Time this suspend blocker has prevented suspend while
+ * user-space requested suspend.
+ * @max_time: Max time this suspend blocker has been continuously active.
+ * @last_time: Monotonic clock when the active state last changed.
+ */
+struct suspend_blocker_stats {
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+ unsigned int count;
+ unsigned int wakeup_count;
+ ktime_t total_time;
+ ktime_t prevent_suspend_time;
+ ktime_t max_time;
+ ktime_t last_time;
+#endif
+};

/**
* struct suspend_blocker - the basic suspend_blocker structure
* @link: List entry for active or inactive list.
- * @flags: Tracks initialized and active state.
+ * @flags: Tracks initialized and active state and statistics.
* @name: Suspend blocker name used for debugging.
*
* When a suspend_blocker is active it prevents the system from entering
@@ -34,6 +58,7 @@ struct suspend_blocker {
struct list_head link;
int flags;
const char *name;
+ struct suspend_blocker_stats stat;
#endif
};

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 2e665cd..16a2570 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -146,6 +146,14 @@ config OPPORTUNISTIC_SUSPEND
determines the sleep state the system will be put into when there are
no active suspend blockers.

+config SUSPEND_BLOCKER_STATS
+ bool "Suspend blockers statistics"
+ depends on OPPORTUNISTIC_SUSPEND
+ default y
+ ---help---
+ Use /sys/kernel/debug/suspend_blockers to report suspend blockers
+ statistics.
+
config USER_SUSPEND_BLOCKERS
bool "User space suspend blockers"
depends on OPPORTUNISTIC_SUSPEND
diff --git a/kernel/power/opportunistic_suspend.c b/kernel/power/opportunistic_suspend.c
index 6b5eb1d..a8824ba 100644
--- a/kernel/power/opportunistic_suspend.c
+++ b/kernel/power/opportunistic_suspend.c
@@ -39,6 +39,7 @@ module_param_named(unknown_wakeup_delay_msecs, unknown_wakeup_delay_msecs, int,

#define SB_INITIALIZED (1U << 8)
#define SB_ACTIVE (1U << 9)
+#define SB_PREVENTING_SUSPEND (1U << 10)

DEFINE_SUSPEND_BLOCKER(main_suspend_blocker, main);

@@ -51,6 +52,117 @@ static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;
static bool enable_suspend_blockers;
static DEFINE_SUSPEND_BLOCKER(unknown_wakeup, unknown_wakeups);

+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+static struct suspend_blocker_stats dropped_suspend_blockers;
+static ktime_t last_sleep_time_update;
+static bool wait_for_wakeup;
+
+static void suspend_blocker_stat_init(struct suspend_blocker_stats *stat)
+{
+ stat->count = 0;
+ stat->wakeup_count = 0;
+ stat->total_time = ktime_set(0, 0);
+ stat->prevent_suspend_time = ktime_set(0, 0);
+ stat->max_time = ktime_set(0, 0);
+ stat->last_time = ktime_set(0, 0);
+}
+
+static void init_dropped_suspend_blockers(void)
+{
+ suspend_blocker_stat_init(&dropped_suspend_blockers);
+}
+
+static void suspend_blocker_stat_drop(struct suspend_blocker_stats *stat)
+{
+ if (!stat->count)
+ return;
+
+ dropped_suspend_blockers.count += stat->count;
+ dropped_suspend_blockers.total_time = ktime_add(
+ dropped_suspend_blockers.total_time, stat->total_time);
+ dropped_suspend_blockers.prevent_suspend_time = ktime_add(
+ dropped_suspend_blockers.prevent_suspend_time,
+ stat->prevent_suspend_time);
+ dropped_suspend_blockers.max_time = ktime_add(
+ dropped_suspend_blockers.max_time, stat->max_time);
+}
+
+static void suspend_unblock_stat(struct suspend_blocker *blocker)
+{
+ struct suspend_blocker_stats *stat = &blocker->stat;
+ ktime_t duration;
+ ktime_t now;
+
+ if (!(blocker->flags & SB_ACTIVE))
+ return;
+
+ now = ktime_get();
+ stat->count++;
+ duration = ktime_sub(now, stat->last_time);
+ stat->total_time = ktime_add(stat->total_time, duration);
+ if (ktime_to_ns(duration) > ktime_to_ns(stat->max_time))
+ stat->max_time = duration;
+
+ stat->last_time = ktime_get();
+ if (blocker->flags & SB_PREVENTING_SUSPEND) {
+ duration = ktime_sub(now, last_sleep_time_update);
+ stat->prevent_suspend_time = ktime_add(
+ stat->prevent_suspend_time, duration);
+ blocker->flags &= ~SB_PREVENTING_SUSPEND;
+ }
+}
+
+static void suspend_block_stat(struct suspend_blocker *blocker)
+{
+ if (wait_for_wakeup) {
+ if (debug_mask & DEBUG_WAKEUP)
+ pr_info("wakeup suspend blocker: %s\n", blocker->name);
+
+ wait_for_wakeup = false;
+ blocker->stat.wakeup_count++;
+ }
+ if (!(blocker->flags & SB_ACTIVE))
+ blocker->stat.last_time = ktime_get();
+}
+
+static void update_sleep_wait_stats(bool done)
+{
+ struct suspend_blocker *blocker;
+ ktime_t now, elapsed, add;
+
+ now = ktime_get();
+ elapsed = ktime_sub(now, last_sleep_time_update);
+ list_for_each_entry(blocker, &active_blockers, link) {
+ struct suspend_blocker_stats *stat = &blocker->stat;
+
+ if (blocker->flags & SB_PREVENTING_SUSPEND) {
+ add = elapsed;
+ stat->prevent_suspend_time = ktime_add(
+ stat->prevent_suspend_time, add);
+ }
+ if (done)
+ blocker->flags &= ~SB_PREVENTING_SUSPEND;
+ else
+ blocker->flags |= SB_PREVENTING_SUSPEND;
+ }
+ last_sleep_time_update = now;
+}
+
+void about_to_enter_suspend(void)
+{
+ wait_for_wakeup = true;
+}
+
+#else /* !CONFIG_SUSPEND_BLOCKER_STATS */
+
+static inline void init_dropped_suspend_blockers(void) {}
+static inline void suspend_blocker_stat_init(struct suspend_blocker_stats *s) {}
+static inline void suspend_blocker_stat_drop(struct suspend_blocker_stats *s) {}
+static inline void suspend_unblock_stat(struct suspend_blocker *blocker) {}
+static inline void suspend_block_stat(struct suspend_blocker *blocker) {}
+static inline void update_sleep_wait_stats(bool done) {}
+#endif /* !CONFIG_SUSPEND_BLOCKER_STATS */
+
#define pr_info_time(fmt, args...) \
do { \
struct timespec ts; \
@@ -140,6 +252,8 @@ void suspend_blocker_register(struct suspend_blocker *blocker)
if (debug_mask & DEBUG_SUSPEND_BLOCKER)
pr_info("%s: Registering %s\n", __func__, blocker->name);

+ suspend_blocker_stat_init(&blocker->stat);
+
blocker->flags = SB_INITIALIZED;
INIT_LIST_HEAD(&blocker->link);

@@ -177,6 +291,10 @@ void suspend_blocker_unregister(struct suspend_blocker *blocker)
return;

spin_lock_irqsave(&list_lock, irqflags);
+
+ suspend_unblock_stat(blocker);
+ suspend_blocker_stat_drop(&blocker->stat);
+
blocker->flags &= ~SB_INITIALIZED;
list_del(&blocker->link);
if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
@@ -206,11 +324,18 @@ void suspend_block(struct suspend_blocker *blocker)
if (debug_mask & DEBUG_SUSPEND_BLOCKER)
pr_info("%s: %s\n", __func__, blocker->name);

+ suspend_block_stat(blocker);
+
blocker->flags |= SB_ACTIVE;
list_move(&blocker->link, &active_blockers);

current_event_num++;

+ if (blocker == &main_suspend_blocker)
+ update_sleep_wait_stats(true);
+ else if (!suspend_blocker_is_active(&main_suspend_blocker))
+ update_sleep_wait_stats(false);
+
spin_unlock_irqrestore(&list_lock, irqflags);
}
EXPORT_SYMBOL(suspend_block);
@@ -235,13 +360,19 @@ void suspend_unblock(struct suspend_blocker *blocker)
if (debug_mask & DEBUG_SUSPEND_BLOCKER)
pr_info("%s: %s\n", __func__, blocker->name);

+ suspend_unblock_stat(blocker);
+
list_move(&blocker->link, &inactive_blockers);
if ((blocker->flags & SB_ACTIVE) && list_empty(&active_blockers))
queue_work(pm_wq, &suspend_work);
blocker->flags &= ~(SB_ACTIVE);

- if ((debug_mask & DEBUG_SUSPEND) && blocker == &main_suspend_blocker)
- print_active_suspend_blockers();
+ if (blocker == &main_suspend_blocker) {
+ if (debug_mask & DEBUG_SUSPEND)
+ print_active_suspend_blockers();
+
+ update_sleep_wait_stats(false);
+ }

spin_unlock_irqrestore(&list_lock, irqflags);
}
@@ -297,10 +428,68 @@ void __init opportunistic_suspend_init(void)
suspend_blocker_register(&main_suspend_blocker);
suspend_block(&main_suspend_blocker);
suspend_blocker_register(&unknown_wakeup);
+ init_dropped_suspend_blockers();
}

static struct dentry *suspend_blocker_stats_dentry;

+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+static int print_blocker_stats(struct seq_file *m, const char *name,
+ struct suspend_blocker_stats *stat, int flags)
+{
+ int lock_count = stat->count;
+ ktime_t active_time = ktime_set(0, 0);
+ ktime_t total_time = stat->total_time;
+ ktime_t max_time = stat->max_time;
+ ktime_t prevent_suspend_time = stat->prevent_suspend_time;
+
+ if (flags & SB_ACTIVE) {
+ ktime_t now, add_time;
+
+ now = ktime_get();
+ add_time = ktime_sub(now, stat->last_time);
+ lock_count++;
+ active_time = add_time;
+ total_time = ktime_add(total_time, add_time);
+ if (flags & SB_PREVENTING_SUSPEND)
+ prevent_suspend_time = ktime_add(prevent_suspend_time,
+ ktime_sub(now, last_sleep_time_update));
+ if (add_time.tv64 > max_time.tv64)
+ max_time = add_time;
+ }
+
+ return seq_printf(m, "\"%s\"\t%d\t%d\t%lld\t%lld\t%lld\t%lld\t%lld\n",
+ name, lock_count, stat->wakeup_count,
+ ktime_to_ns(active_time), ktime_to_ns(total_time),
+ ktime_to_ns(prevent_suspend_time),
+ ktime_to_ns(max_time),
+ ktime_to_ns(stat->last_time));
+}
+
+static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
+{
+ unsigned long irqflags;
+ struct suspend_blocker *blocker;
+
+ seq_puts(m, "name\tcount\twake_count\tactive_since"
+ "\ttotal_time\tsleep_time\tmax_time\tlast_change\n");
+
+ spin_lock_irqsave(&list_lock, irqflags);
+ list_for_each_entry(blocker, &active_blockers, link)
+ print_blocker_stats(m,
+ blocker->name, &blocker->stat, blocker->flags);
+
+ list_for_each_entry(blocker, &inactive_blockers, link)
+ print_blocker_stats(m,
+ blocker->name, &blocker->stat, blocker->flags);
+
+ print_blocker_stats(m, "deleted", &dropped_suspend_blockers, 0);
+ spin_unlock_irqrestore(&list_lock, irqflags);
+ return 0;
+}
+
+#else
+
static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
{
unsigned long irqflags;
@@ -316,6 +505,8 @@ static int suspend_blocker_stats_show(struct seq_file *m, void *unused)
return 0;
}

+#endif
+
static int suspend_blocker_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, suspend_blocker_stats_show, NULL);
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 2e9cfd5..e13c975 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -245,3 +245,8 @@ extern void __init opportunistic_suspend_init(void);
#else
static inline void opportunistic_suspend_init(void) {}
#endif
+#ifdef CONFIG_SUSPEND_BLOCKER_STATS
+void about_to_enter_suspend(void);
+#else
+static inline void about_to_enter_suspend(void) {}
+#endif
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 9eb3876..df694e7 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -158,8 +158,10 @@ static int suspend_enter(suspend_state_t state)

error = sysdev_suspend(PMSG_SUSPEND);
if (!error) {
- if (!suspend_is_blocked() && !suspend_test(TEST_CORE))
+ if (!suspend_is_blocked() && !suspend_test(TEST_CORE)) {
+ about_to_enter_suspend();
error = suspend_ops->enter(state);
+ }
sysdev_resume();
}

--
1.6.5.1
--
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