diff options
author | Joe Thornber <ejt@redhat.com> | 2014-10-06 18:27:26 +0400 |
---|---|---|
committer | Mike Snitzer <snitzer@redhat.com> | 2014-11-10 23:25:26 +0300 |
commit | 4646015d7e4ca5a4dc19427fb0a0aeff15a4fd91 (patch) | |
tree | 5afe82e874f9eff6eeb70e77db458b22dcea3307 /drivers | |
parent | e5cfc69a513cdc9d9e753c5ce07f0cc6b496bfd3 (diff) | |
download | linux-4646015d7e4ca5a4dc19427fb0a0aeff15a4fd91.tar.xz |
dm transaction manager: add support for prefetching blocks of metadata
Introduce the dm_tm_issue_prefetches interface. If you're using a
non-blocking clone the tm will build up a list of requested blocks that
weren't in core. dm_tm_issue_prefetches will request those blocks to be
prefetched.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/md/persistent-data/dm-transaction-manager.c | 77 | ||||
-rw-r--r-- | drivers/md/persistent-data/dm-transaction-manager.h | 7 |
2 files changed, 82 insertions, 2 deletions
diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c index 3bc30a0ae3d6..9cb797d800cf 100644 --- a/drivers/md/persistent-data/dm-transaction-manager.c +++ b/drivers/md/persistent-data/dm-transaction-manager.c @@ -10,6 +10,8 @@ #include "dm-persistent-data-internal.h" #include <linux/export.h> +#include <linux/mutex.h> +#include <linux/hash.h> #include <linux/slab.h> #include <linux/device-mapper.h> @@ -17,6 +19,61 @@ /*----------------------------------------------------------------*/ +#define PREFETCH_SIZE 128 +#define PREFETCH_BITS 7 +#define PREFETCH_SENTINEL ((dm_block_t) -1ULL) + +struct prefetch_set { + struct mutex lock; + dm_block_t blocks[PREFETCH_SIZE]; +}; + +static unsigned prefetch_hash(dm_block_t b) +{ + return hash_64(b, PREFETCH_BITS); +} + +static void prefetch_wipe(struct prefetch_set *p) +{ + unsigned i; + for (i = 0; i < PREFETCH_SIZE; i++) + p->blocks[i] = PREFETCH_SENTINEL; +} + +static void prefetch_init(struct prefetch_set *p) +{ + mutex_init(&p->lock); + prefetch_wipe(p); +} + +static void prefetch_add(struct prefetch_set *p, dm_block_t b) +{ + unsigned h = prefetch_hash(b); + + mutex_lock(&p->lock); + if (p->blocks[h] == PREFETCH_SENTINEL) + p->blocks[h] = b; + + mutex_unlock(&p->lock); +} + +static void prefetch_issue(struct prefetch_set *p, struct dm_block_manager *bm) +{ + unsigned i; + + mutex_lock(&p->lock); + + for (i = 0; i < PREFETCH_SIZE; i++) + if (p->blocks[i] != PREFETCH_SENTINEL) { + dm_bm_prefetch(bm, p->blocks[i]); + p->blocks[i] = PREFETCH_SENTINEL; + } + + mutex_unlock(&p->lock); +} + +/*----------------------------------------------------------------*/ + struct shadow_info { struct hlist_node hlist; dm_block_t where; @@ -37,6 +94,8 @@ struct dm_transaction_manager { spinlock_t lock; struct hlist_head buckets[DM_HASH_SIZE]; + + struct prefetch_set prefetches; }; /*----------------------------------------------------------------*/ @@ -117,6 +176,8 @@ static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm, for (i = 0; i < DM_HASH_SIZE; i++) INIT_HLIST_HEAD(tm->buckets + i); + prefetch_init(&tm->prefetches); + return tm; } @@ -268,8 +329,14 @@ int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b, struct dm_block_validator *v, struct dm_block **blk) { - if (tm->is_clone) - return dm_bm_read_try_lock(tm->real->bm, b, v, blk); + if (tm->is_clone) { + int r = dm_bm_read_try_lock(tm->real->bm, b, v, blk); + + if (r == -EWOULDBLOCK) + prefetch_add(&tm->real->prefetches, b); + + return r; + } return dm_bm_read_lock(tm->bm, b, v, blk); } @@ -317,6 +384,12 @@ struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm) return tm->bm; } +void dm_tm_issue_prefetches(struct dm_transaction_manager *tm) +{ + prefetch_issue(&tm->prefetches, tm->bm); +} +EXPORT_SYMBOL_GPL(dm_tm_issue_prefetches); + /*----------------------------------------------------------------*/ static int dm_tm_create_internal(struct dm_block_manager *bm, diff --git a/drivers/md/persistent-data/dm-transaction-manager.h b/drivers/md/persistent-data/dm-transaction-manager.h index 2772ed2a781a..2e0d4d66fb1b 100644 --- a/drivers/md/persistent-data/dm-transaction-manager.h +++ b/drivers/md/persistent-data/dm-transaction-manager.h @@ -109,6 +109,13 @@ int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b, struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm); /* + * If you're using a non-blocking clone the tm will build up a list of + * requested blocks that weren't in core. This call will request those + * blocks to be prefetched. + */ +void dm_tm_issue_prefetches(struct dm_transaction_manager *tm); + +/* * A little utility that ties the knot by producing a transaction manager * that has a space map managed by the transaction manager... * |