blkio: Changes to IO controller additional stats patches

that include some minor fixes and addresses all comments.

Changelog: (most based on Vivek Goyal's comments)
o renamed blkiocg_reset_write to blkiocg_reset_stats
o more clarification in the documentation on io_service_time and io_wait_time
o Initialize blkg->stats_lock
o rename io_add_stat to blkio_add_stat and declare it static
o use bool for direction and sync
o derive direction and sync info from existing rq methods
o use 12 for major:minor string length
o define io_service_time better to cover the NCQ case
o add a separate reset_stats interface
o make the indexed stats a 2d array to simplify macro and function pointer code
o blkio.time now exports in jiffies as before
o Added stats description in patch description and
  Documentation/cgroup/blkio-controller.txt
o Prefix all stats functions with blkio and make them static as applicable
o replace IO_TYPE_MAX with IO_TYPE_TOTAL
o Moved #define constant to top of blk-cgroup.c
o Pass dev_t around instead of char *
o Add note to documentation file about resetting stats
o use BLK_CGROUP_MODULE in addition to BLK_CGROUP config option in #ifdef
  statements
o Avoid struct request specific knowledge in blk-cgroup. blk-cgroup.h now has
  rq_direction() and rq_sync() functions which are used by CFQ and when using
  io-controller at a higher level, bio_* functions can be added.

Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 39 insertions, 25 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 80010ef64ab0..b22e55390a4f 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -23,12 +23,31 @@ extern struct cgroup_subsys blkio_subsys;
 #define blkio_subsys_id blkio_subsys.subsys_id
 #endif
 
-enum io_type {
-        IO_READ = 0,
-        IO_WRITE,
-        IO_SYNC,
-        IO_ASYNC,
-        IO_TYPE_MAX
+enum stat_type {
+        /* Total time spent (in ns) between request dispatch to the driver and
+         * request completion for IOs doen by this cgroup. This may not be
+         * accurate when NCQ is turned on. */
+        BLKIO_STAT_SERVICE_TIME = 0,
+        /* Total bytes transferred */
+        BLKIO_STAT_SERVICE_BYTES,
+        /* Total IOs serviced, post merge */
+        BLKIO_STAT_SERVICED,
+        /* Total time spent waiting in scheduler queue in ns */
+        BLKIO_STAT_WAIT_TIME,
+        /* All the single valued stats go below this */
+        BLKIO_STAT_TIME,
+        BLKIO_STAT_SECTORS,
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+        BLKIO_STAT_DEQUEUE
+#endif
+};
+
+enum stat_sub_type {
+        BLKIO_STAT_READ = 0,
+        BLKIO_STAT_WRITE,
+        BLKIO_STAT_SYNC,
+        BLKIO_STAT_ASYNC,
+        BLKIO_STAT_TOTAL
 };
 
 struct blkio_cgroup {
@@ -42,13 +61,7 @@ struct blkio_group_stats {
         /* total disk time and nr sectors dispatched by this group */
         uint64_t time;
         uint64_t sectors;
-        /* Total disk time used by IOs in ns */
-        uint64_t io_service_time[IO_TYPE_MAX];
-        uint64_t io_service_bytes[IO_TYPE_MAX]; /* Total bytes transferred */
-        /* Total IOs serviced, post merge */
-        uint64_t io_serviced[IO_TYPE_MAX];
-        /* Total time spent waiting in scheduler queue in ns */
-        uint64_t io_wait_time[IO_TYPE_MAX];
+        uint64_t stat_arr[BLKIO_STAT_WAIT_TIME + 1][BLKIO_STAT_TOTAL];
 #ifdef CONFIG_DEBUG_BLK_CGROUP
         /* How many times this group has been removed from service tree */
         unsigned long dequeue;
@@ -65,7 +78,7 @@ struct blkio_group {
         char path[128];
 #endif
         /* The device MKDEV(major, minor), this group has been created for */
-        dev_t   dev;
+        dev_t dev;
 
         /* Need to serialize the stats in the case of reset/update */
         spinlock_t stats_lock;
@@ -128,21 +141,21 @@ extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
 extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
                                                 void *key);
+void blkio_group_init(struct blkio_group *blkg);
 void blkiocg_update_timeslice_used(struct blkio_group *blkg,
                                         unsigned long time);
-void blkiocg_update_request_dispatch_stats(struct blkio_group *blkg,
-                                                struct request *rq);
-void blkiocg_update_request_completion_stats(struct blkio_group *blkg,
-                                                struct request *rq);
+void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,
+                                                bool direction, bool sync);
+void blkiocg_update_completion_stats(struct blkio_group *blkg,
+        uint64_t start_time, uint64_t io_start_time, bool direction, bool sync);
 #else
 struct cgroup;
 static inline struct blkio_cgroup *
 cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
 
+static inline void blkio_group_init(struct blkio_group *blkg) {}
 static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
-                        struct blkio_group *blkg, void *key, dev_t dev)
-{
-}
+                        struct blkio_group *blkg, void *key, dev_t dev) {}
 
 static inline int
 blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
@@ -151,9 +164,10 @@ static inline struct blkio_group *
 blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
 static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,
                                                 unsigned long time) {}
-static inline void blkiocg_update_request_dispatch_stats(
-                struct blkio_group *blkg, struct request *rq) {}
-static inline void blkiocg_update_request_completion_stats(
-                struct blkio_group *blkg, struct request *rq) {}
+static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
+                                uint64_t bytes, bool direction, bool sync) {}
+static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,
+                uint64_t start_time, uint64_t io_start_time, bool direction,
+                bool sync) {}
 #endif
 #endif /* _BLK_CGROUP_H */