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Subject[PATCH 2/4] io-controller: a new interface to keep track of the time since group bacame backlogged
A new interface to keep track of the time elapsed since group became
backlogged. Will be reset when group enqueued.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
---
block/blk-cgroup.c | 42 +++++++++++++++++++++++++++++++++++++++++-
block/blk-cgroup.h | 9 +++++++++
block/cfq-iosched.c | 14 ++++++++++++++
3 files changed, 64 insertions(+), 1 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 749fc6b..5b47655 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -308,6 +308,20 @@ void blkiocg_reset_active_bytes(struct blkio_group *blkg)
}
EXPORT_SYMBOL_GPL(blkiocg_reset_active_bytes);

+void blkiocg_update_active_start_time(struct blkio_group *blkg)
+{
+ struct blkio_group_stats *stats;
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkg->stats_lock, flags);
+
+ stats = &blkg->stats;
+ stats->active_start_time = get_jiffies_64();
+
+ spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_active_start_time);
+
void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
uint64_t bytes, bool direction, bool sync)
{
@@ -568,6 +582,8 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
uint64_t disk_total;
char key_str[MAX_KEY_LEN];
enum stat_sub_type sub_type;
+ struct blkio_policy_type *blkiop;
+ int ret;

if (type == BLKIO_STAT_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
@@ -575,6 +591,26 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
if (type == BLKIO_STAT_SECTORS)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
blkg->stats.sectors, cb, dev);
+ if (type == BLKIO_STAT_ACTIVE_TIME) {
+ uint64_t delta;
+
+ delta = get_jiffies_64() -
+ blkg->stats.active_start_time;
+
+ delta = jiffies_to_msecs(delta);
+ list_for_each_entry(blkiop, &blkio_list, list) {
+ ret = blkiop->ops.blkio_is_blkg_active_fn(blkg);
+ /* If group isn't backlogged, don't show */
+ if (!ret) {
+ delta = 0;
+ break;
+ }
+ }
+
+ return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+ delta, cb, dev);
+ }
+
#ifdef CONFIG_DEBUG_BLK_CGROUP
if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
uint64_t sum = blkg->stats.avg_queue_size_sum;
@@ -644,6 +680,7 @@ SHOW_FUNCTION_PER_GROUP(time, BLKIO_STAT_TIME, 0);
SHOW_FUNCTION_PER_GROUP(sectors, BLKIO_STAT_SECTORS, 0);
SHOW_FUNCTION_PER_GROUP(io_service_bytes, BLKIO_STAT_SERVICE_BYTES, 1);
SHOW_FUNCTION_PER_GROUP(io_active_bytes, BLKIO_STAT_ACTIVE_BYTES, 1);
+SHOW_FUNCTION_PER_GROUP(io_active_time, BLKIO_STAT_ACTIVE_TIME, 0);
SHOW_FUNCTION_PER_GROUP(io_serviced, BLKIO_STAT_SERVICED, 1);
SHOW_FUNCTION_PER_GROUP(io_service_time, BLKIO_STAT_SERVICE_TIME, 1);
SHOW_FUNCTION_PER_GROUP(io_wait_time, BLKIO_STAT_WAIT_TIME, 1);
@@ -873,7 +910,10 @@ struct cftype blkio_files[] = {
.name = "io_active_bytes",
.read_map = blkiocg_io_active_bytes_read,
},
-
+ {
+ .name = "io_active_time",
+ .read_map = blkiocg_io_active_time_read,
+ },
{
.name = "io_serviced",
.read_map = blkiocg_io_serviced_read,
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 67d4284..2ae7976 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -35,6 +35,11 @@ enum stat_type {
* when group dequeued.
*/
BLKIO_STAT_ACTIVE_BYTES,
+ /*
+ * Total time (in ms) elapsed since group became backlogged, will
+ * reset when group enqueued.
+ */
+ BLKIO_STAT_ACTIVE_TIME,
/* Total IOs serviced, post merge */
BLKIO_STAT_SERVICED,
/* Total time spent waiting in scheduler queue in ns */
@@ -83,6 +88,7 @@ struct blkio_group_stats {
uint64_t time;
uint64_t sectors;
uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
+ uint64_t active_start_time;
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Sum of number of IOs queued across all samples */
uint64_t avg_queue_size_sum;
@@ -135,10 +141,12 @@ extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg,
unsigned int weight);
+typedef bool (blkio_is_blkg_active) (struct blkio_group *blkg);

struct blkio_policy_ops {
blkio_unlink_group_fn *blkio_unlink_group_fn;
blkio_update_group_weight_fn *blkio_update_group_weight_fn;
+ blkio_is_blkg_active *blkio_is_blkg_active_fn;
};

struct blkio_policy_type {
@@ -150,6 +158,7 @@ struct blkio_policy_type {
extern void blkio_policy_register(struct blkio_policy_type *);
extern void blkio_policy_unregister(struct blkio_policy_type *);
extern void blkiocg_reset_active_bytes(struct blkio_group *);
+extern void blkiocg_update_active_start_time(struct blkio_group *);

static inline char *blkg_path(struct blkio_group *blkg)
{
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d4a3525..b21ae10 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -834,6 +834,7 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
__cfq_group_service_tree_add(st, cfqg);
cfqg->on_st = true;
st->total_weight += cfqg->weight;
+ blkiocg_update_active_start_time(&cfqg->blkg);
}

static void
@@ -930,6 +931,18 @@ static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
return NULL;
}

+bool is_blkg_active(struct blkio_group *blkg)
+{
+ struct cfq_group *cfqg;
+
+ cfqg = cfqg_of_blkg(blkg);
+ if (cfqg && cfqg->on_st)
+ return true;
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(is_blkg_active);
+
void
cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
{
@@ -3944,6 +3957,7 @@ static struct blkio_policy_type blkio_policy_cfq = {
.ops = {
.blkio_unlink_group_fn = cfq_unlink_blkio_group,
.blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
+ .blkio_is_blkg_active_fn = is_blkg_active,
},
};
#else
-- 1.5.4.rc3

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