diff options
| -rw-r--r-- | drivers/md/dm-cache-policy-mq.c | 94 |
1 files changed, 93 insertions, 1 deletions
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c index 6bfb394..3ddd116 100644 --- a/drivers/md/dm-cache-policy-mq.c +++ b/drivers/md/dm-cache-policy-mq.c @@ -8,6 +8,7 @@ #include "dm.h" #include <linux/hash.h> +#include <linux/jiffies.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/slab.h> @@ -126,8 +127,12 @@ static void iot_examine_bio(struct io_tracker *t, struct bio *bio) #define NR_QUEUE_LEVELS 16u #define NR_SENTINELS NR_QUEUE_LEVELS * 3 +#define WRITEBACK_PERIOD HZ + struct queue { unsigned nr_elts; + bool current_writeback_sentinels; + unsigned long next_writeback; struct list_head qs[NR_QUEUE_LEVELS]; struct list_head sentinels[NR_SENTINELS]; }; @@ -137,12 +142,21 @@ static void queue_init(struct queue *q) unsigned i; q->nr_elts = 0; + q->current_writeback_sentinels = false; + q->next_writeback = 0; for (i = 0; i < NR_QUEUE_LEVELS; i++) { INIT_LIST_HEAD(q->qs + i); INIT_LIST_HEAD(q->sentinels + i); + INIT_LIST_HEAD(q->sentinels + NR_QUEUE_LEVELS + i); + INIT_LIST_HEAD(q->sentinels + (2 * NR_QUEUE_LEVELS) + i); } } +static unsigned queue_size(struct queue *q) +{ + return q->nr_elts; +} + static bool queue_empty(struct queue *q) { return q->nr_elts == 0; @@ -197,6 +211,27 @@ static struct list_head *queue_pop(struct queue *q) return r; } +/* + * Pops an entry from a level that is not past a sentinel. + */ +static struct list_head *queue_pop_old(struct queue *q) +{ + unsigned level; + struct list_head *h; + + for (level = 0; level < NR_QUEUE_LEVELS; level++) + list_for_each(h, q->qs + level) { + if (is_sentinel(q, h)) + break; + + q->nr_elts--; + list_del(h); + return h; + } + + return NULL; +} + static struct list_head *list_pop(struct list_head *lh) { struct list_head *r = lh->next; @@ -207,6 +242,31 @@ static struct list_head *list_pop(struct list_head *lh) return r; } +static struct list_head *writeback_sentinel(struct queue *q, unsigned level) +{ + if (q->current_writeback_sentinels) + return q->sentinels + NR_QUEUE_LEVELS + level; + else + return q->sentinels + 2 * NR_QUEUE_LEVELS + level; +} + +static void queue_update_writeback_sentinels(struct queue *q) +{ + unsigned i; + struct list_head *h; + + if (time_after(jiffies, q->next_writeback)) { + for (i = 0; i < NR_QUEUE_LEVELS; i++) { + h = writeback_sentinel(q, i); + list_del(h); + list_add_tail(h, q->qs + i); + } + + q->next_writeback = jiffies + WRITEBACK_PERIOD; + q->current_writeback_sentinels = !q->current_writeback_sentinels; + } +} + /* * Sometimes we want to iterate through entries that have been pushed since * a certain event. We use sentinel entries on the queues to delimit these @@ -540,6 +600,20 @@ static struct entry *pop(struct mq_policy *mq, struct queue *q) return e; } +static struct entry *pop_old(struct mq_policy *mq, struct queue *q) +{ + struct entry *e; + struct list_head *h = queue_pop_old(q); + + if (!h) + return NULL; + + e = container_of(h, struct entry, list); + hash_remove(e); + + return e; +} + static struct entry *peek(struct queue *q) { struct list_head *h = queue_peek(q); @@ -932,6 +1006,7 @@ static void copy_tick(struct mq_policy *mq) queue_tick(&mq->pre_cache); queue_tick(&mq->cache_dirty); queue_tick(&mq->cache_clean); + queue_update_writeback_sentinels(&mq->cache_dirty); spin_unlock_irqrestore(&mq->tick_lock, flags); } @@ -1112,10 +1187,27 @@ static int mq_remove_cblock(struct dm_cache_policy *p, dm_cblock_t cblock) return r; } +#define CLEAN_TARGET_PERCENTAGE 25 + +static bool clean_target_met(struct mq_policy *mq) +{ + /* + * Cache entries may not be populated. So we're cannot rely on the + * size of the clean queue. + */ + unsigned nr_clean = from_cblock(mq->cache_size) - queue_size(&mq->cache_dirty); + unsigned target = from_cblock(mq->cache_size) * CLEAN_TARGET_PERCENTAGE / 100; + + return nr_clean >= target; +} + static int __mq_writeback_work(struct mq_policy *mq, dm_oblock_t *oblock, dm_cblock_t *cblock) { - struct entry *e = pop(mq, &mq->cache_dirty); + struct entry *e = pop_old(mq, &mq->cache_dirty); + + if (!e && !clean_target_met(mq)) + e = pop(mq, &mq->cache_dirty); if (!e) return -ENODATA; |
