aboutsummaryrefslogtreecommitdiffstats
path: root/block/blk-cgroup.c
diff options
context:
space:
mode:
authorDivyesh Shah <dpshah@google.com>2010-04-09 04:15:10 (GMT)
committerJens Axboe <jens.axboe@oracle.com>2010-04-09 06:36:08 (GMT)
commitcdc1184cf4a7bd99f5473a91244197accc49146b (patch)
treeecd572867bfa5a82fa4ed16d7303448c7ea7d24c /block/blk-cgroup.c
parent812d402648f4fc1ab1091b2172a46fc1b367c724 (diff)
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>
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c98
1 files changed, 93 insertions, 5 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d23b538..1e0c497 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -81,6 +81,71 @@ static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
stat[BLKIO_STAT_ASYNC] += add;
}
+/*
+ * Decrements the appropriate stat variable if non-zero depending on the
+ * request type. Panics on value being zero.
+ * This should be called with the blkg->stats_lock held.
+ */
+static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
+{
+ if (direction) {
+ BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
+ stat[BLKIO_STAT_WRITE]--;
+ } else {
+ BUG_ON(stat[BLKIO_STAT_READ] == 0);
+ stat[BLKIO_STAT_READ]--;
+ }
+ if (sync) {
+ BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
+ stat[BLKIO_STAT_SYNC]--;
+ } else {
+ BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
+ stat[BLKIO_STAT_ASYNC]--;
+ }
+}
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+void blkiocg_update_set_active_queue_stats(struct blkio_group *blkg)
+{
+ unsigned long flags;
+ struct blkio_group_stats *stats;
+
+ spin_lock_irqsave(&blkg->stats_lock, flags);
+ stats = &blkg->stats;
+ stats->avg_queue_size_sum +=
+ stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
+ stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
+ stats->avg_queue_size_samples++;
+ spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_set_active_queue_stats);
+#endif
+
+void blkiocg_update_request_add_stats(struct blkio_group *blkg,
+ struct blkio_group *curr_blkg, bool direction,
+ bool sync)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkg->stats_lock, flags);
+ blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
+ sync);
+ spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_request_add_stats);
+
+void blkiocg_update_request_remove_stats(struct blkio_group *blkg,
+ bool direction, bool sync)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkg->stats_lock, flags);
+ blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
+ direction, sync);
+ spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_request_remove_stats);
+
void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
{
unsigned long flags;
@@ -253,14 +318,18 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
struct blkio_cgroup *blkcg;
struct blkio_group *blkg;
struct hlist_node *n;
- struct blkio_group_stats *stats;
+ uint64_t queued[BLKIO_STAT_TOTAL];
+ int i;
blkcg = cgroup_to_blkio_cgroup(cgroup);
spin_lock_irq(&blkcg->lock);
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
spin_lock(&blkg->stats_lock);
- stats = &blkg->stats;
- memset(stats, 0, sizeof(struct blkio_group_stats));
+ for (i = 0; i < BLKIO_STAT_TOTAL; i++)
+ queued[i] = blkg->stats.stat_arr[BLKIO_STAT_QUEUED][i];
+ memset(&blkg->stats, 0, sizeof(struct blkio_group_stats));
+ for (i = 0; i < BLKIO_STAT_TOTAL; i++)
+ blkg->stats.stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
spin_unlock(&blkg->stats_lock);
}
spin_unlock_irq(&blkcg->lock);
@@ -323,6 +392,15 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
blkg->stats.sectors, cb, dev);
#ifdef CONFIG_DEBUG_BLK_CGROUP
+ if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
+ uint64_t sum = blkg->stats.avg_queue_size_sum;
+ uint64_t samples = blkg->stats.avg_queue_size_samples;
+ if (samples)
+ do_div(sum, samples);
+ else
+ sum = 0;
+ return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
+ }
if (type == BLKIO_STAT_DEQUEUE)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
blkg->stats.dequeue, cb, dev);
@@ -376,8 +454,10 @@ 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);
SHOW_FUNCTION_PER_GROUP(io_merged, BLKIO_STAT_MERGED, 1);
+SHOW_FUNCTION_PER_GROUP(io_queued, BLKIO_STAT_QUEUED, 1);
#ifdef CONFIG_DEBUG_BLK_CGROUP
SHOW_FUNCTION_PER_GROUP(dequeue, BLKIO_STAT_DEQUEUE, 0);
+SHOW_FUNCTION_PER_GROUP(avg_queue_size, BLKIO_STAT_AVG_QUEUE_SIZE, 0);
#endif
#undef SHOW_FUNCTION_PER_GROUP
@@ -425,14 +505,22 @@ struct cftype blkio_files[] = {
.read_map = blkiocg_io_merged_read,
},
{
+ .name = "io_queued",
+ .read_map = blkiocg_io_queued_read,
+ },
+ {
.name = "reset_stats",
.write_u64 = blkiocg_reset_stats,
},
#ifdef CONFIG_DEBUG_BLK_CGROUP
- {
+ {
+ .name = "avg_queue_size",
+ .read_map = blkiocg_avg_queue_size_read,
+ },
+ {
.name = "dequeue",
.read_map = blkiocg_dequeue_read,
- },
+ },
#endif
};

Privacy Policy