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authorDivyesh Shah <dpshah@google.com>2010-04-09 04:14:23 (GMT)
committerJens Axboe <jens.axboe@oracle.com>2010-04-09 06:36:07 (GMT)
commit812d402648f4fc1ab1091b2172a46fc1b367c724 (patch)
tree9dc52d5bfdbc170559169a0157ed3295d551e9cf /block/blk-cgroup.c
parent84c124da9ff50bd71fab9c939ee5b7cd8bef2bd9 (diff)
blkio: Add io_merged stat
This includes both the number of bios merged into requests belonging to this cgroup as well as the number of requests merged together. In the past, we've observed different merging behavior across upstream kernels, some by design some actual bugs. This stat helps a lot in debugging such problems when applications report decreased throughput with a new kernel version. This needed adding an extra elevator function to capture bios being merged as I did not want to pollute elevator code with blkiocg knowledge and hence needed the accounting invocation to come from CFQ. 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.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 6797df50..d23b538 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -127,6 +127,18 @@ void blkiocg_update_completion_stats(struct blkio_group *blkg,
}
EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
+void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
+ bool sync)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkg->stats_lock, flags);
+ blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
+ sync);
+ spin_unlock_irqrestore(&blkg->stats_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
+
void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
struct blkio_group *blkg, void *key, dev_t dev)
{
@@ -363,6 +375,7 @@ SHOW_FUNCTION_PER_GROUP(io_service_bytes, BLKIO_STAT_SERVICE_BYTES, 1);
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);
#ifdef CONFIG_DEBUG_BLK_CGROUP
SHOW_FUNCTION_PER_GROUP(dequeue, BLKIO_STAT_DEQUEUE, 0);
#endif
@@ -408,6 +421,10 @@ struct cftype blkio_files[] = {
.read_map = blkiocg_io_wait_time_read,
},
{
+ .name = "io_merged",
+ .read_map = blkiocg_io_merged_read,
+ },
+ {
.name = "reset_stats",
.write_u64 = blkiocg_reset_stats,
},

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