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authorHannes Reinecke <hare@suse.de>2014-11-05 14:35:50 +0100
committerMike Snitzer <snitzer@redhat.com>2014-11-10 15:25:29 -0500
commit41abc4e1af369bb5438eaee398e3beee690cc8ca (patch)
treea94881ff00d7e3ab5d42544670c77a6bff8224ef /drivers/md
parent6fa9952097747f71c5077f3e14ce3f8adee6f778 (diff)
dm: do not call dm_sync_table() when creating new devices
When creating new devices dm_sync_table() calls synchronize_rcu_expedited(), causing _all_ pending RCU pointers to be flushed. This causes a latency overhead that is especially noticeable when creating lots of devices. And all of this is pointless as there are no old maps to be disconnected, and hence no stale pointers which would need to be cleared up. Signed-off-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 16a806a99b99..866ff19aa438 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2341,7 +2341,8 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
else
clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
- dm_sync_table(md);
+ if (old_map)
+ dm_sync_table(md);
return old_map;
}
@@ -2782,7 +2783,8 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
* flush_workqueue(md->wq).
*/
set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
- synchronize_srcu(&md->io_barrier);
+ if (map)
+ synchronize_srcu(&md->io_barrier);
/*
* Stop md->queue before flushing md->wq in case request-based
@@ -2802,7 +2804,8 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
if (noflush)
clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
- synchronize_srcu(&md->io_barrier);
+ if (map)
+ synchronize_srcu(&md->io_barrier);
/* were we interrupted ? */
if (r < 0) {

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