dm cache: make the 'mq' policy an alias for 'smq'
smq seems to be performing better than the old mq policy in all
situations, as well as using a quarter of the memory.
Make 'mq' an alias for 'smq' when choosing a cache policy. The tunables
that were present for the old mq are faked, and have no effect. mq
should be considered deprecated now.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-cache-policy-smq.c b/drivers/md/dm-cache-policy-smq.c
index 28d4586..a3e8e74 100644
--- a/drivers/md/dm-cache-policy-smq.c
+++ b/drivers/md/dm-cache-policy-smq.c
@@ -1567,8 +1567,48 @@
spin_unlock_irqrestore(&mq->lock, flags);
}
+/*
+ * smq has no config values, but the old mq policy did. To avoid breaking
+ * software we continue to accept these configurables for the mq policy,
+ * but they have no effect.
+ */
+static int mq_set_config_value(struct dm_cache_policy *p,
+ const char *key, const char *value)
+{
+ unsigned long tmp;
+
+ if (kstrtoul(value, 10, &tmp))
+ return -EINVAL;
+
+ if (!strcasecmp(key, "random_threshold") ||
+ !strcasecmp(key, "sequential_threshold") ||
+ !strcasecmp(key, "discard_promote_adjustment") ||
+ !strcasecmp(key, "read_promote_adjustment") ||
+ !strcasecmp(key, "write_promote_adjustment")) {
+ DMWARN("tunable '%s' no longer has any effect, mq policy is now an alias for smq", key);
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static int mq_emit_config_values(struct dm_cache_policy *p, char *result,
+ unsigned maxlen, ssize_t *sz_ptr)
+{
+ ssize_t sz = *sz_ptr;
+
+ DMEMIT("10 random_threshold 0 "
+ "sequential_threshold 0 "
+ "discard_promote_adjustment 0 "
+ "read_promote_adjustment 0 "
+ "write_promote_adjustment 0 ");
+
+ *sz_ptr = sz;
+ return 0;
+}
+
/* Init the policy plugin interface function pointers. */
-static void init_policy_functions(struct smq_policy *mq)
+static void init_policy_functions(struct smq_policy *mq, bool mimic_mq)
{
mq->policy.destroy = smq_destroy;
mq->policy.map = smq_map;
@@ -1583,6 +1623,11 @@
mq->policy.force_mapping = smq_force_mapping;
mq->policy.residency = smq_residency;
mq->policy.tick = smq_tick;
+
+ if (mimic_mq) {
+ mq->policy.set_config_value = mq_set_config_value;
+ mq->policy.emit_config_values = mq_emit_config_values;
+ }
}
static bool too_many_hotspot_blocks(sector_t origin_size,
@@ -1606,9 +1651,10 @@
*hotspot_block_size /= 2u;
}
-static struct dm_cache_policy *smq_create(dm_cblock_t cache_size,
- sector_t origin_size,
- sector_t cache_block_size)
+static struct dm_cache_policy *__smq_create(dm_cblock_t cache_size,
+ sector_t origin_size,
+ sector_t cache_block_size,
+ bool mimic_mq)
{
unsigned i;
unsigned nr_sentinels_per_queue = 2u * NR_CACHE_LEVELS;
@@ -1618,7 +1664,7 @@
if (!mq)
return NULL;
- init_policy_functions(mq);
+ init_policy_functions(mq, mimic_mq);
mq->cache_size = cache_size;
mq->cache_block_size = cache_block_size;
@@ -1706,19 +1752,41 @@
return NULL;
}
+static struct dm_cache_policy *smq_create(dm_cblock_t cache_size,
+ sector_t origin_size,
+ sector_t cache_block_size)
+{
+ return __smq_create(cache_size, origin_size, cache_block_size, false);
+}
+
+static struct dm_cache_policy *mq_create(dm_cblock_t cache_size,
+ sector_t origin_size,
+ sector_t cache_block_size)
+{
+ return __smq_create(cache_size, origin_size, cache_block_size, true);
+}
+
/*----------------------------------------------------------------*/
static struct dm_cache_policy_type smq_policy_type = {
.name = "smq",
- .version = {1, 0, 0},
+ .version = {1, 5, 0},
.hint_size = 4,
.owner = THIS_MODULE,
.create = smq_create
};
+static struct dm_cache_policy_type mq_policy_type = {
+ .name = "mq",
+ .version = {1, 5, 0},
+ .hint_size = 4,
+ .owner = THIS_MODULE,
+ .create = mq_create,
+};
+
static struct dm_cache_policy_type default_policy_type = {
.name = "default",
- .version = {1, 4, 0},
+ .version = {1, 5, 0},
.hint_size = 4,
.owner = THIS_MODULE,
.create = smq_create,
@@ -1735,9 +1803,17 @@
return -ENOMEM;
}
+ r = dm_cache_policy_register(&mq_policy_type);
+ if (r) {
+ DMERR("register failed %d", r);
+ dm_cache_policy_unregister(&smq_policy_type);
+ return -ENOMEM;
+ }
+
r = dm_cache_policy_register(&default_policy_type);
if (r) {
DMERR("register failed (as default) %d", r);
+ dm_cache_policy_unregister(&mq_policy_type);
dm_cache_policy_unregister(&smq_policy_type);
return -ENOMEM;
}
@@ -1748,6 +1824,7 @@
static void __exit smq_exit(void)
{
dm_cache_policy_unregister(&smq_policy_type);
+ dm_cache_policy_unregister(&mq_policy_type);
dm_cache_policy_unregister(&default_policy_type);
}
@@ -1759,3 +1836,4 @@
MODULE_DESCRIPTION("smq cache policy");
MODULE_ALIAS("dm-cache-default");
+MODULE_ALIAS("dm-cache-mq");