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authorJoe Thornber <ejt@redhat.com>2013-08-09 15:59:30 +0400
committerMike Snitzer <snitzer@redhat.com>2013-08-23 17:02:14 +0400
commit04f17c802f447e76d13ade5bb78fbbf34baef0f8 (patch)
tree4bca7fac638c13e0659824e566dbd8df58f148dc /drivers/md
parentcd5acf0b445030cd8b5bfd818f464997652485e5 (diff)
downloadlinux-04f17c802f447e76d13ade5bb78fbbf34baef0f8.tar.xz
dm btree: prefetch child nodes when walking tree for a dm_btree_del
dm-btree now takes advantage of dm-bufio's ability to prefetch data via dm_bm_prefetch(). Prior to this change many btree node visits were causing a synchronous read. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/persistent-data/dm-block-manager.c5
-rw-r--r--drivers/md/persistent-data/dm-block-manager.h5
-rw-r--r--drivers/md/persistent-data/dm-btree.c26
3 files changed, 31 insertions, 5 deletions
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index 81b513890e2b..a7e8bf296388 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -615,6 +615,11 @@ int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
}
EXPORT_SYMBOL_GPL(dm_bm_flush_and_unlock);
+void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b)
+{
+ dm_bufio_prefetch(bm->bufio, b, 1);
+}
+
void dm_bm_set_read_only(struct dm_block_manager *bm)
{
bm->read_only = true;
diff --git a/drivers/md/persistent-data/dm-block-manager.h b/drivers/md/persistent-data/dm-block-manager.h
index be5bff61be28..9a82083a66b6 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -108,6 +108,11 @@ int dm_bm_unlock(struct dm_block *b);
int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
struct dm_block *superblock);
+ /*
+ * Request data be prefetched into the cache.
+ */
+void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b);
+
/*
* Switches the bm to a read only mode. Once read-only mode
* has been entered the following functions will return -EPERM.
diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index e872996e098d..468e371ee9b2 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -161,6 +161,7 @@ struct frame {
};
struct del_stack {
+ struct dm_btree_info *info;
struct dm_transaction_manager *tm;
int top;
struct frame spine[MAX_SPINE_DEPTH];
@@ -183,6 +184,20 @@ static int unprocessed_frames(struct del_stack *s)
return s->top >= 0;
}
+static void prefetch_children(struct del_stack *s, struct frame *f)
+{
+ unsigned i;
+ struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
+
+ for (i = 0; i < f->nr_children; i++)
+ dm_bm_prefetch(bm, value64(f->n, i));
+}
+
+static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
+{
+ return f->level < (info->levels - 1);
+}
+
static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
{
int r;
@@ -205,6 +220,7 @@ static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
dm_tm_dec(s->tm, b);
else {
+ uint32_t flags;
struct frame *f = s->spine + ++s->top;
r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
@@ -217,6 +233,10 @@ static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
f->level = level;
f->nr_children = le32_to_cpu(f->n->header.nr_entries);
f->current_child = 0;
+
+ flags = le32_to_cpu(f->n->header.flags);
+ if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
+ prefetch_children(s, f);
}
return 0;
@@ -230,11 +250,6 @@ static void pop_frame(struct del_stack *s)
dm_tm_unlock(s->tm, f->b);
}
-static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
-{
- return f->level < (info->levels - 1);
-}
-
int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
{
int r;
@@ -243,6 +258,7 @@ int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
+ s->info = info;
s->tm = info->tm;
s->top = -1;