diff options
Diffstat (limited to 'drivers/md/dm-cache-policy-mq.c')
| -rw-r--r-- | drivers/md/dm-cache-policy-mq.c | 82 |
1 files changed, 54 insertions, 28 deletions
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c index 0e385e40909e..13f547a4eeb6 100644 --- a/drivers/md/dm-cache-policy-mq.c +++ b/drivers/md/dm-cache-policy-mq.c @@ -181,24 +181,30 @@ static void queue_shift_down(struct queue *q) * Gives us the oldest entry of the lowest popoulated level. If the first * level is emptied then we shift down one level. */ -static struct list_head *queue_pop(struct queue *q) +static struct list_head *queue_peek(struct queue *q) { unsigned level; - struct list_head *r; for (level = 0; level < NR_QUEUE_LEVELS; level++) - if (!list_empty(q->qs + level)) { - r = q->qs[level].next; - list_del(r); + if (!list_empty(q->qs + level)) + return q->qs[level].next; - /* have we just emptied the bottom level? */ - if (level == 0 && list_empty(q->qs)) - queue_shift_down(q); + return NULL; +} - return r; - } +static struct list_head *queue_pop(struct queue *q) +{ + struct list_head *r = queue_peek(q); - return NULL; + if (r) { + list_del(r); + + /* have we just emptied the bottom level? */ + if (list_empty(q->qs)) + queue_shift_down(q); + } + + return r; } static struct list_head *list_pop(struct list_head *lh) @@ -383,13 +389,6 @@ struct mq_policy { unsigned generation; unsigned generation_period; /* in lookups (will probably change) */ - /* - * Entries in the pre_cache whose hit count passes the promotion - * threshold move to the cache proper. Working out the correct - * value for the promotion_threshold is crucial to this policy. - */ - unsigned promote_threshold; - unsigned discard_promote_adjustment; unsigned read_promote_adjustment; unsigned write_promote_adjustment; @@ -406,6 +405,7 @@ struct mq_policy { #define DEFAULT_DISCARD_PROMOTE_ADJUSTMENT 1 #define DEFAULT_READ_PROMOTE_ADJUSTMENT 4 #define DEFAULT_WRITE_PROMOTE_ADJUSTMENT 8 +#define DISCOURAGE_DEMOTING_DIRTY_THRESHOLD 128 /*----------------------------------------------------------------*/ @@ -518,6 +518,12 @@ static struct entry *pop(struct mq_policy *mq, struct queue *q) return e; } +static struct entry *peek(struct queue *q) +{ + struct list_head *h = queue_peek(q); + return h ? container_of(h, struct entry, list) : NULL; +} + /* * Has this entry already been updated? */ @@ -570,10 +576,6 @@ static void check_generation(struct mq_policy *mq) break; } } - - mq->promote_threshold = nr ? total / nr : 1; - if (mq->promote_threshold * nr < total) - mq->promote_threshold++; } } @@ -641,6 +643,30 @@ static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) } /* + * Entries in the pre_cache whose hit count passes the promotion + * threshold move to the cache proper. Working out the correct + * value for the promotion_threshold is crucial to this policy. + */ +static unsigned promote_threshold(struct mq_policy *mq) +{ + struct entry *e; + + if (any_free_cblocks(mq)) + return 0; + + e = peek(&mq->cache_clean); + if (e) + return e->hit_count; + + e = peek(&mq->cache_dirty); + if (e) + return e->hit_count + DISCOURAGE_DEMOTING_DIRTY_THRESHOLD; + + /* This should never happen */ + return 0; +} + +/* * We modify the basic promotion_threshold depending on the specific io. * * If the origin block has been discarded then there's no cost to copy it @@ -653,7 +679,7 @@ static unsigned adjusted_promote_threshold(struct mq_policy *mq, bool discarded_oblock, int data_dir) { if (data_dir == READ) - return mq->promote_threshold + mq->read_promote_adjustment; + return promote_threshold(mq) + mq->read_promote_adjustment; if (discarded_oblock && (any_free_cblocks(mq) || any_clean_cblocks(mq))) { /* @@ -663,7 +689,7 @@ static unsigned adjusted_promote_threshold(struct mq_policy *mq, return mq->discard_promote_adjustment; } - return mq->promote_threshold + mq->write_promote_adjustment; + return promote_threshold(mq) + mq->write_promote_adjustment; } static bool should_promote(struct mq_policy *mq, struct entry *e, @@ -839,7 +865,8 @@ static int map(struct mq_policy *mq, dm_oblock_t oblock, if (e && in_cache(mq, e)) r = cache_entry_found(mq, e, result); - else if (iot_pattern(&mq->tracker) == PATTERN_SEQUENTIAL) + else if (mq->tracker.thresholds[PATTERN_SEQUENTIAL] && + iot_pattern(&mq->tracker) == PATTERN_SEQUENTIAL) result->op = POLICY_MISS; else if (e) @@ -1230,7 +1257,6 @@ static struct dm_cache_policy *mq_create(dm_cblock_t cache_size, mq->tick = 0; mq->hit_count = 0; mq->generation = 0; - mq->promote_threshold = 0; mq->discard_promote_adjustment = DEFAULT_DISCARD_PROMOTE_ADJUSTMENT; mq->read_promote_adjustment = DEFAULT_READ_PROMOTE_ADJUSTMENT; mq->write_promote_adjustment = DEFAULT_WRITE_PROMOTE_ADJUSTMENT; @@ -1265,7 +1291,7 @@ bad_pre_cache_init: static struct dm_cache_policy_type mq_policy_type = { .name = "mq", - .version = {1, 2, 0}, + .version = {1, 3, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create @@ -1273,7 +1299,7 @@ static struct dm_cache_policy_type mq_policy_type = { static struct dm_cache_policy_type default_policy_type = { .name = "default", - .version = {1, 2, 0}, + .version = {1, 3, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create, |