On Fri, Nov 18, 2016 at 09:26:22AM -0800, Shaohua Li wrote:
> On Fri, Nov 18, 2016 at 01:22:04PM +1100, Neil Brown wrote:
> >
> > The block tracing infrastructure (accessed with blktrace/blkparse)
> > supports the tracing of mapping bios from one device to another.
> > This is currently used when a bio in a partition is mapped to the
> > whole device, when bios are mapped by dm, and for mapping in md/raid5.
> > Other md personalities do not include this tracing yet, so add it.
> >
> > When a read-error is detected we redirect the request to a different device.
> > This could justifiably be seen as a new mapping for the originial bio,
> > or a secondary mapping for the bio that errors. This patch uses
> > the second option.
> >
> > When md is used under dm-raid, the mappings are not traced as we do
> > not have access to the block device number of the parent.
>
> thanks, applied patch 1, 3, 4.
BTW, I added below patch
commit 504634f60f463e73e7d58c6810a04437da942dba
Author: Shaohua Li <shli@xxxxxx>
Date: Fri Nov 18 09:44:08 2016 -0800
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@xxxxxx>
Cc: NeilBrown <neilb@xxxxxxxx>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1f1c7f0..d3cef77 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -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 @@ void md_update_sb(struct mddev *mddev, int force_change)
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];
--
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