HST need to know the IO start time in order to predict path
performance. For request-based multipath use the block layer
io_start_time, while for BIO use the dm_io start_time.
The dm_start_time_ns_from_clone function was suggested and implemented
by Mike Snitzer <snitzer@xxxxxxxxxx>.
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
---
drivers/md/dm-mpath.c | 25 +++++++++++++++----------
drivers/md/dm-path-selector.h | 1 +
drivers/md/dm.c | 10 ++++++++++
include/linux/device-mapper.h | 2 ++
4 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 1ef4fc2e745b..7af3249948be 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -500,8 +500,9 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
struct dm_mpath_io *mpio = get_mpio(map_context);
struct request_queue *q;
struct request *clone;
- struct path_selector_io_data io_data = {
+ struct path_selector_io_data ps_io_data = {
.nr_bytes = nr_bytes,
+ .io_start_time = rq->io_start_time_ns
};
/* Do we need to select a new pgpath? */
@@ -552,7 +553,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
- &io_data);
+ &ps_io_data);
return DM_MAPIO_REMAPPED;
}
@@ -568,6 +569,7 @@ static void multipath_release_clone(struct request *clone,
struct pgpath *pgpath = mpio->pgpath;
struct path_selector_io_data ps_io_data = {
.nr_bytes = mpio->nr_bytes,
+ .io_start_time = clone->io_start_time_ns,
};
if (pgpath && pgpath->pg->ps.type->end_io)
@@ -623,8 +625,9 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio,
struct dm_mpath_io *mpio)
{
struct pgpath *pgpath = __map_bio(m, bio);
- struct path_selector_io_data io_data = {
+ struct path_selector_io_data ps_io_data = {
.nr_bytes = mpio->nr_bytes,
+ .io_start_time = dm_start_time_ns_from_clone(bio)
};
if (IS_ERR(pgpath))
@@ -646,7 +649,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio,
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
- &io_data);
+ &ps_io_data);
return DM_MAPIO_REMAPPED;
}
@@ -1627,12 +1630,13 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
if (pgpath) {
struct path_selector *ps = &pgpath->pg->ps;
- struct path_selector_io_data io_data = {
- .nr_bytes = mpio->nr_bytes
+ struct path_selector_io_data ps_io_data = {
+ .nr_bytes = mpio->nr_bytes,
+ .io_start_time = clone->io_start_time_ns
};
if (ps->type->end_io)
- ps->type->end_io(ps, &pgpath->path, &io_data);
+ ps->type->end_io(ps, &pgpath->path, &ps_io_data);
}
return r;
@@ -1674,12 +1678,13 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
done:
if (pgpath) {
struct path_selector *ps = &pgpath->pg->ps;
- struct path_selector_io_data io_data = {
- .nr_bytes = mpio->nr_bytes
+ struct path_selector_io_data ps_io_data = {
+ .nr_bytes = mpio->nr_bytes,
+ .io_start_time = dm_start_time_ns_from_clone(clone)
};
if (ps->type->end_io)
- ps->type->end_io(ps, &pgpath->path, &io_data);
+ ps->type->end_io(ps, &pgpath->path, &ps_io_data);
}
return r;
diff --git a/drivers/md/dm-path-selector.h b/drivers/md/dm-path-selector.h
index fb582a943234..4c5fa6a2efe3 100644
--- a/drivers/md/dm-path-selector.h
+++ b/drivers/md/dm-path-selector.h
@@ -28,6 +28,7 @@ struct path_selector {
struct path_selector_io_data {
size_t nr_bytes;
+ u64 io_start_time;
};
/* Information about a path selector type */
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index df13fdebe21f..2e0637a6de9d 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -674,6 +674,16 @@ static bool md_in_flight(struct mapped_device *md)
return md_in_flight_bios(md);
}
+u64 dm_start_time_ns_from_clone(struct bio *bio)
+{
+ struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
+ struct dm_io *io = tio->io;
+
+ /* FIXME: convert io->start_time from jiffies to nanoseconds */
+ return (u64)jiffies_to_msecs(io->start_time) * NSEC_PER_MSEC;
+}
+EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);
+
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 475668c69dbc..e2d506dd805e 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -329,6 +329,8 @@ void *dm_per_bio_data(struct bio *bio, size_t data_size);
struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size);
unsigned dm_bio_get_target_bio_nr(const struct bio *bio);
+u64 dm_start_time_ns_from_clone(struct bio *bio);
+
int dm_register_target(struct target_type *t);
void dm_unregister_target(struct target_type *t);
--
2.26.2
--
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