Messages in this thread Patch in this message | | | Date | Wed, 20 Jul 2011 20:29:21 -0400 (EDT) | From | Mikulas Patocka <> | Subject | [PATCH] backing-dev: use synchronize_rcu_expedited instead of synchronize_rcu |
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Hi Jens
Please would you consider taking this into the block tree? It seems to speed up device deletion enormously.
Mikulas
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backing-dev: use synchronize_rcu_expedited instead of synchronize_rcu
synchronize_rcu sleeps several timer ticks. synchronize_rcu_expedited is much faster.
With 100Hz timer frequency, when we remove 10000 block devices with "dmsetup remove_all" command, it takes 27 minutes. With this patch, removing 10000 block devices takes only 15 seconds.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
--- mm/backing-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-3.0-rc7-fast/mm/backing-dev.c =================================================================== --- linux-3.0-rc7-fast.orig/mm/backing-dev.c 2011-07-19 18:01:00.000000000 +0200 +++ linux-3.0-rc7-fast/mm/backing-dev.c 2011-07-19 18:01:07.000000000 +0200 @@ -505,7 +505,7 @@ static void bdi_remove_from_list(struct list_del_rcu(&bdi->bdi_list); spin_unlock_bh(&bdi_lock); - synchronize_rcu(); + synchronize_rcu_expedited(); } int bdi_register(struct backing_dev_info *bdi, struct device *parent,
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