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dm btree: prefetch child nodes when walking tree for a dm_btree_del

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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>
This commit is contained in:
Joe Thornber 2013-08-09 12:59:30 +01:00 committed by Mike Snitzer
parent cd5acf0b44
commit 04f17c802f
3 changed files with 31 additions and 5 deletions
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5
drivers/md/persistent-data/dm-block-manager.c
View File

@ -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;

5
drivers/md/persistent-data/dm-block-manager.h
View File

@ -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.

26
drivers/md/persistent-data/dm-btree.c
View File

@ -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;