diff options
| -rw-r--r-- | drivers/md/dm-cache-policy-mq.c | 84 |
1 files changed, 63 insertions, 21 deletions
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c index 6710e038c730..444f0bf10b21 100644 --- a/drivers/md/dm-cache-policy-mq.c +++ b/drivers/md/dm-cache-policy-mq.c @@ -151,6 +151,21 @@ static void queue_init(struct queue *q) } /* + * Checks to see if the queue is empty. + * FIXME: reduce cpu usage. + */ +static bool queue_empty(struct queue *q) +{ + unsigned i; + + for (i = 0; i < NR_QUEUE_LEVELS; i++) + if (!list_empty(q->qs + i)) + return false; + + return true; +} + +/* * Insert an entry to the back of the given level. */ static void queue_push(struct queue *q, unsigned level, struct list_head *elt) @@ -442,6 +457,11 @@ static bool any_free_cblocks(struct mq_policy *mq) return mq->nr_cblocks_allocated < from_cblock(mq->cache_size); } +static bool any_clean_cblocks(struct mq_policy *mq) +{ + return !queue_empty(&mq->cache_clean); +} + /* * Fills result out with a cache block that isn't in use, or return * -ENOSPC. This does _not_ mark the cblock as allocated, the caller is @@ -688,17 +708,18 @@ static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock, dm_cblock_t static unsigned adjusted_promote_threshold(struct mq_policy *mq, bool discarded_oblock, int data_dir) { - if (discarded_oblock && any_free_cblocks(mq) && data_dir == WRITE) + if (data_dir == READ) + return mq->promote_threshold + READ_PROMOTE_THRESHOLD; + + if (discarded_oblock && (any_free_cblocks(mq) || any_clean_cblocks(mq))) { /* * We don't need to do any copying at all, so give this a - * very low threshold. In practice this only triggers - * during initial population after a format. + * very low threshold. */ return DISCARDED_PROMOTE_THRESHOLD; + } - return data_dir == READ ? - (mq->promote_threshold + READ_PROMOTE_THRESHOLD) : - (mq->promote_threshold + WRITE_PROMOTE_THRESHOLD); + return mq->promote_threshold + WRITE_PROMOTE_THRESHOLD; } static bool should_promote(struct mq_policy *mq, struct entry *e, @@ -772,6 +793,17 @@ static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e, return r; } +static void insert_entry_in_pre_cache(struct mq_policy *mq, + struct entry *e, dm_oblock_t oblock) +{ + e->in_cache = false; + e->dirty = false; + e->oblock = oblock; + e->hit_count = 1; + e->generation = mq->generation; + push(mq, e); +} + static void insert_in_pre_cache(struct mq_policy *mq, dm_oblock_t oblock) { @@ -789,30 +821,41 @@ static void insert_in_pre_cache(struct mq_policy *mq, return; } - e->in_cache = false; - e->dirty = false; - e->oblock = oblock; - e->hit_count = 1; - e->generation = mq->generation; - push(mq, e); + insert_entry_in_pre_cache(mq, e, oblock); } static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, struct policy_result *result) { + int r; struct entry *e; dm_cblock_t cblock; if (find_free_cblock(mq, &cblock) == -ENOSPC) { - result->op = POLICY_MISS; - insert_in_pre_cache(mq, oblock); - return; - } + r = demote_cblock(mq, &result->old_oblock, &cblock); + if (unlikely(r)) { + result->op = POLICY_MISS; + insert_in_pre_cache(mq, oblock); + return; + } - e = alloc_entry(mq); - if (unlikely(!e)) { - result->op = POLICY_MISS; - return; + /* + * This will always succeed, since we've just demoted. + */ + e = pop(mq, &mq->pre_cache); + result->op = POLICY_REPLACE; + + } else { + e = alloc_entry(mq); + if (unlikely(!e)) + e = pop(mq, &mq->pre_cache); + + if (unlikely(!e)) { + result->op = POLICY_MISS; + return; + } + + result->op = POLICY_NEW; } e->oblock = oblock; @@ -823,7 +866,6 @@ static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, e->generation = mq->generation; push(mq, e); - result->op = POLICY_NEW; result->cblock = e->cblock; } |