md: add blktrace event for writes to superblock

superblock write is an expensive operation. With raid5-cache, it can be called
regularly. Tracing to help performance debug.

Signed-off-by: Shaohua Li <shli@fb.com>
Cc: NeilBrown <neilb@suse.com>
This commit is contained in:
Shaohua Li 2016-11-18 09:44:08 -08:00
parent 578b54ade8
commit 504634f60f

View File

@ -64,6 +64,7 @@
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include <linux/slab.h>
#include <trace/events/block.h>
#include "md.h"
#include "bitmap.h"
#include "md-cluster.h"
@ -2403,6 +2404,8 @@ repeat:
pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
mdname(mddev), mddev->in_sync);
if (mddev->queue)
blk_add_trace_msg(mddev->queue, "md md_update_sb");
bitmap_update_sb(mddev->bitmap);
rdev_for_each(rdev, mddev) {
char b[BDEVNAME_SIZE];