diff options
| -rw-r--r-- | Documentation/device-mapper/cache-policies.txt | 16 | ||||
| -rw-r--r-- | drivers/md/dm-cache-policy-mq.c | 64 |
2 files changed, 57 insertions, 23 deletions
diff --git a/Documentation/device-mapper/cache-policies.txt b/Documentation/device-mapper/cache-policies.txt index df52a849957f..66c2774c0c64 100644 --- a/Documentation/device-mapper/cache-policies.txt +++ b/Documentation/device-mapper/cache-policies.txt @@ -40,8 +40,11 @@ on hit count on entry. The policy aims to take different cache miss costs into account and to adjust to varying load patterns automatically. Message and constructor argument pairs are: - 'sequential_threshold <#nr_sequential_ios>' and - 'random_threshold <#nr_random_ios>'. + 'sequential_threshold <#nr_sequential_ios>' + 'random_threshold <#nr_random_ios>' + 'read_promote_adjustment <value>' + 'write_promote_adjustment <value>' + 'discard_promote_adjustment <value>' The sequential threshold indicates the number of contiguous I/Os required before a stream is treated as sequential. The random threshold @@ -55,6 +58,15 @@ since spindles tend to have good bandwidth. The io_tracker counts contiguous I/Os to try to spot when the io is in one of these sequential modes. +Internally the mq policy maintains a promotion threshold variable. If +the hit count of a block not in the cache goes above this threshold it +gets promoted to the cache. The read, write and discard promote adjustment +tunables allow you to tweak the promotion threshold by adding a small +value based on the io type. They default to 4, 8 and 1 respectively. +If you're trying to quickly warm a new cache device you may wish to +reduce these to encourage promotion. Remember to switch them back to +their defaults after the cache fills though. + cleaner ------- diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c index 7f1aaa38a7e0..e63e36cefc89 100644 --- a/drivers/md/dm-cache-policy-mq.c +++ b/drivers/md/dm-cache-policy-mq.c @@ -390,6 +390,10 @@ struct mq_policy { */ unsigned promote_threshold; + unsigned discard_promote_adjustment; + unsigned read_promote_adjustment; + unsigned write_promote_adjustment; + /* * The hash table allows us to quickly find an entry by origin * block. Both pre_cache and cache entries are in here. @@ -399,6 +403,10 @@ struct mq_policy { struct hlist_head *table; }; +#define DEFAULT_DISCARD_PROMOTE_ADJUSTMENT 1 +#define DEFAULT_READ_PROMOTE_ADJUSTMENT 4 +#define DEFAULT_WRITE_PROMOTE_ADJUSTMENT 8 + /*----------------------------------------------------------------*/ /* @@ -641,25 +649,21 @@ static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) * We bias towards reads, since they can be demoted at no cost if they * haven't been dirtied. */ -#define DISCARDED_PROMOTE_THRESHOLD 1 -#define READ_PROMOTE_THRESHOLD 4 -#define WRITE_PROMOTE_THRESHOLD 8 - static unsigned adjusted_promote_threshold(struct mq_policy *mq, bool discarded_oblock, int data_dir) { if (data_dir == READ) - return mq->promote_threshold + READ_PROMOTE_THRESHOLD; + return mq->promote_threshold + mq->read_promote_adjustment; 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. */ - return DISCARDED_PROMOTE_THRESHOLD; + return mq->discard_promote_adjustment; } - return mq->promote_threshold + WRITE_PROMOTE_THRESHOLD; + return mq->promote_threshold + mq->write_promote_adjustment; } static bool should_promote(struct mq_policy *mq, struct entry *e, @@ -808,7 +812,7 @@ static int no_entry_found(struct mq_policy *mq, dm_oblock_t oblock, bool can_migrate, bool discarded_oblock, int data_dir, struct policy_result *result) { - if (adjusted_promote_threshold(mq, discarded_oblock, data_dir) == 1) { + if (adjusted_promote_threshold(mq, discarded_oblock, data_dir) <= 1) { if (can_migrate) insert_in_cache(mq, oblock, result); else @@ -1134,20 +1138,28 @@ static int mq_set_config_value(struct dm_cache_policy *p, const char *key, const char *value) { struct mq_policy *mq = to_mq_policy(p); - enum io_pattern pattern; unsigned long tmp; - if (!strcasecmp(key, "random_threshold")) - pattern = PATTERN_RANDOM; - else if (!strcasecmp(key, "sequential_threshold")) - pattern = PATTERN_SEQUENTIAL; - else - return -EINVAL; - if (kstrtoul(value, 10, &tmp)) return -EINVAL; - mq->tracker.thresholds[pattern] = tmp; + if (!strcasecmp(key, "random_threshold")) { + mq->tracker.thresholds[PATTERN_RANDOM] = tmp; + + } else if (!strcasecmp(key, "sequential_threshold")) { + mq->tracker.thresholds[PATTERN_SEQUENTIAL] = tmp; + + } else if (!strcasecmp(key, "discard_promote_adjustment")) + mq->discard_promote_adjustment = tmp; + + else if (!strcasecmp(key, "read_promote_adjustment")) + mq->read_promote_adjustment = tmp; + + else if (!strcasecmp(key, "write_promote_adjustment")) + mq->write_promote_adjustment = tmp; + + else + return -EINVAL; return 0; } @@ -1157,9 +1169,16 @@ static int mq_emit_config_values(struct dm_cache_policy *p, char *result, unsign ssize_t sz = 0; struct mq_policy *mq = to_mq_policy(p); - DMEMIT("4 random_threshold %u sequential_threshold %u", + DMEMIT("10 random_threshold %u " + "sequential_threshold %u " + "discard_promote_adjustment %u " + "read_promote_adjustment %u " + "write_promote_adjustment %u", mq->tracker.thresholds[PATTERN_RANDOM], - mq->tracker.thresholds[PATTERN_SEQUENTIAL]); + mq->tracker.thresholds[PATTERN_SEQUENTIAL], + mq->discard_promote_adjustment, + mq->read_promote_adjustment, + mq->write_promote_adjustment); return 0; } @@ -1212,6 +1231,9 @@ static struct dm_cache_policy *mq_create(dm_cblock_t cache_size, 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; mutex_init(&mq->lock); spin_lock_init(&mq->tick_lock); @@ -1243,7 +1265,7 @@ bad_pre_cache_init: static struct dm_cache_policy_type mq_policy_type = { .name = "mq", - .version = {1, 1, 0}, + .version = {1, 2, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create @@ -1251,7 +1273,7 @@ static struct dm_cache_policy_type mq_policy_type = { static struct dm_cache_policy_type default_policy_type = { .name = "default", - .version = {1, 1, 0}, + .version = {1, 2, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create |