blkio: Add io_queued and avg_queue_size stats
These stats are useful for getting a feel for the queue depth of the cgroup,
i.e., how filled up its queues are at a given instant and over the existence of
the cgroup. This ability is useful when debugging problems in the wild as it
helps understand the application's IO pattern w/o having to read through the
userspace code (coz its tedious or just not available) or w/o the ability
to run blktrace (since you may not have root access and/or not want to disturb
performance).
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 470a29d..bea7f3b 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -36,10 +36,13 @@
BLKIO_STAT_WAIT_TIME,
/* Number of IOs merged */
BLKIO_STAT_MERGED,
+ /* Number of IOs queued up */
+ BLKIO_STAT_QUEUED,
/* All the single valued stats go below this */
BLKIO_STAT_TIME,
BLKIO_STAT_SECTORS,
#ifdef CONFIG_DEBUG_BLK_CGROUP
+ BLKIO_STAT_AVG_QUEUE_SIZE,
BLKIO_STAT_DEQUEUE
#endif
};
@@ -63,8 +66,12 @@
/* total disk time and nr sectors dispatched by this group */
uint64_t time;
uint64_t sectors;
- uint64_t stat_arr[BLKIO_STAT_MERGED + 1][BLKIO_STAT_TOTAL];
+ uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
#ifdef CONFIG_DEBUG_BLK_CGROUP
+ /* Sum of number of IOs queued across all samples */
+ uint64_t avg_queue_size_sum;
+ /* Count of samples taken for average */
+ uint64_t avg_queue_size_samples;
/* How many times this group has been removed from service tree */
unsigned long dequeue;
#endif
@@ -127,10 +134,13 @@
{
return blkg->path;
}
+void blkiocg_update_set_active_queue_stats(struct blkio_group *blkg);
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue);
#else
static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
+static inline void blkiocg_update_set_active_queue_stats(
+ struct blkio_group *blkg) {}
static inline void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue) {}
#endif
@@ -152,6 +162,10 @@
uint64_t start_time, uint64_t io_start_time, bool direction, bool sync);
void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
bool sync);
+void blkiocg_update_request_add_stats(struct blkio_group *blkg,
+ struct blkio_group *curr_blkg, bool direction, bool sync);
+void blkiocg_update_request_remove_stats(struct blkio_group *blkg,
+ bool direction, bool sync);
#else
struct cgroup;
static inline struct blkio_cgroup *
@@ -175,5 +189,9 @@
bool sync) {}
static inline void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
bool direction, bool sync) {}
+static inline void blkiocg_update_request_add_stats(struct blkio_group *blkg,
+ struct blkio_group *curr_blkg, bool direction, bool sync) {}
+static inline void blkiocg_update_request_remove_stats(struct blkio_group *blkg,
+ bool direction, bool sync) {}
#endif
#endif /* _BLK_CGROUP_H */