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authorJens Axboe <axboe@fb.com>2016-11-07 21:32:37 -0700
committerJens Axboe <axboe@fb.com>2016-11-10 13:53:26 -0700
commitcf43e6be865a582ba66ee4747ae27a0513f6bba1 (patch)
tree53b71dd2f456e4880428683631fd09c9dc0747a5 /block/blk-sysfs.c
parentebc4ff661fbe76781c6b16dfb7b754a5d5073f8e (diff)
downloadlinux-0-day-cf43e6be865a582ba66ee4747ae27a0513f6bba1.tar.gz
block: add scalable completion tracking of requests
For legacy block, we simply track them in the request queue. For blk-mq, we track them on a per-sw queue basis, which we can then sum up through the hardware queues and finally to a per device state. The stats are tracked in, roughly, 0.1s interval windows. Add sysfs files to display the stats. The feature is off by default, to avoid any extra overhead. In-kernel users of it can turn it on by setting QUEUE_FLAG_STATS in the queue flags. We currently don't turn it on if someone just reads any of the stats files, that is something we could add as well. Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r--block/blk-sysfs.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 488c2e2..9cdb724 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -401,6 +401,26 @@ static ssize_t queue_dax_show(struct request_queue *q, char *page)
return queue_var_show(blk_queue_dax(q), page);
}
+static ssize_t print_stat(char *page, struct blk_rq_stat *stat, const char *pre)
+{
+ return sprintf(page, "%s samples=%llu, mean=%lld, min=%lld, max=%lld\n",
+ pre, (long long) stat->nr_samples,
+ (long long) stat->mean, (long long) stat->min,
+ (long long) stat->max);
+}
+
+static ssize_t queue_stats_show(struct request_queue *q, char *page)
+{
+ struct blk_rq_stat stat[2];
+ ssize_t ret;
+
+ blk_queue_stat_get(q, stat);
+
+ ret = print_stat(page, &stat[BLK_STAT_READ], "read :");
+ ret += print_stat(page + ret, &stat[BLK_STAT_WRITE], "write:");
+ return ret;
+}
+
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
.show = queue_requests_show,
@@ -553,6 +573,11 @@ static struct queue_sysfs_entry queue_dax_entry = {
.show = queue_dax_show,
};
+static struct queue_sysfs_entry queue_stats_entry = {
+ .attr = {.name = "stats", .mode = S_IRUGO },
+ .show = queue_stats_show,
+};
+
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
@@ -582,6 +607,7 @@ static struct attribute *default_attrs[] = {
&queue_poll_entry.attr,
&queue_wc_entry.attr,
&queue_dax_entry.attr,
+ &queue_stats_entry.attr,
NULL,
};