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authorJoe Thornber <ejt@redhat.com>2016-09-15 16:23:46 +0300
committerMike Snitzer <snitzer@redhat.com>2016-09-22 18:15:02 +0300
commit4e781b498ee5008ede91362d91404a362e7a46b3 (patch)
tree039f3914f839b455759253fb0395a639a1912dae
parentdd6a77d99859ab963503e67372ed278fe8ceab26 (diff)
downloadlinux-4e781b498ee5008ede91362d91404a362e7a46b3.tar.xz
dm cache: speed up writing of the hint array
It's far quicker to always delete the hint array and recreate with dm_array_new() because we avoid the copying caused by mutation. Also simplifies the policy interface, replacing the walk_hints() with the simpler get_hint(). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r--drivers/md/dm-cache-metadata.c80
-rw-r--r--drivers/md/dm-cache-policy-cleaner.c2
-rw-r--r--drivers/md/dm-cache-policy-internal.h6
-rw-r--r--drivers/md/dm-cache-policy-smq.c38
-rw-r--r--drivers/md/dm-cache-policy.h10
5 files changed, 42 insertions, 94 deletions
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 3970cda10080..a60f10a0ee0a 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -1368,10 +1368,24 @@ int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
/*----------------------------------------------------------------*/
-static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
+static int get_hint(uint32_t index, void *value_le, void *context)
+{
+ uint32_t value;
+ struct dm_cache_policy *policy = context;
+
+ value = policy_get_hint(policy, to_cblock(index));
+ *((__le32 *) value_le) = cpu_to_le32(value);
+
+ return 0;
+}
+
+/*
+ * It's quicker to always delete the hint array, and recreate with
+ * dm_array_new().
+ */
+static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
{
int r;
- __le32 value;
size_t hint_size;
const char *policy_name = dm_cache_policy_get_name(policy);
const unsigned *policy_version = dm_cache_policy_get_version(policy);
@@ -1380,63 +1394,23 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po
(strlen(policy_name) > sizeof(cmd->policy_name) - 1))
return -EINVAL;
- if (!policy_unchanged(cmd, policy)) {
- strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
- memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
+ strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
+ memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
- hint_size = dm_cache_policy_get_hint_size(policy);
- if (!hint_size)
- return 0; /* short-circuit hints initialization */
- cmd->policy_hint_size = hint_size;
+ hint_size = dm_cache_policy_get_hint_size(policy);
+ if (!hint_size)
+ return 0; /* short-circuit hints initialization */
+ cmd->policy_hint_size = hint_size;
- if (cmd->hint_root) {
- r = dm_array_del(&cmd->hint_info, cmd->hint_root);
- if (r)
- return r;
- }
-
- r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
+ if (cmd->hint_root) {
+ r = dm_array_del(&cmd->hint_info, cmd->hint_root);
if (r)
return r;
-
- value = cpu_to_le32(0);
- __dm_bless_for_disk(&value);
- r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
- from_cblock(cmd->cache_blocks),
- &value, &cmd->hint_root);
- if (r)
- return r;
- }
-
- return 0;
-}
-
-static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
-{
- struct dm_cache_metadata *cmd = context;
- __le32 value = cpu_to_le32(hint);
- int r;
-
- __dm_bless_for_disk(&value);
-
- r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
- from_cblock(cblock), &value, &cmd->hint_root);
- cmd->changed = true;
-
- return r;
-}
-
-static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
-{
- int r;
-
- r = begin_hints(cmd, policy);
- if (r) {
- DMERR("begin_hints failed");
- return r;
}
- return policy_walk_mappings(policy, save_hint, cmd);
+ return dm_array_new(&cmd->hint_info, &cmd->hint_root,
+ from_cblock(cmd->cache_blocks),
+ get_hint, policy);
}
int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
diff --git a/drivers/md/dm-cache-policy-cleaner.c b/drivers/md/dm-cache-policy-cleaner.c
index 14aaaf059f06..2e8a8f1d8358 100644
--- a/drivers/md/dm-cache-policy-cleaner.c
+++ b/drivers/md/dm-cache-policy-cleaner.c
@@ -395,7 +395,7 @@ static void init_policy_functions(struct policy *p)
p->policy.set_dirty = wb_set_dirty;
p->policy.clear_dirty = wb_clear_dirty;
p->policy.load_mapping = wb_load_mapping;
- p->policy.walk_mappings = NULL;
+ p->policy.get_hint = NULL;
p->policy.remove_mapping = wb_remove_mapping;
p->policy.writeback_work = wb_writeback_work;
p->policy.force_mapping = wb_force_mapping;
diff --git a/drivers/md/dm-cache-policy-internal.h b/drivers/md/dm-cache-policy-internal.h
index 2816018faa7f..808ee0e2b2c4 100644
--- a/drivers/md/dm-cache-policy-internal.h
+++ b/drivers/md/dm-cache-policy-internal.h
@@ -48,10 +48,10 @@ static inline int policy_load_mapping(struct dm_cache_policy *p,
return p->load_mapping(p, oblock, cblock, hint, hint_valid);
}
-static inline int policy_walk_mappings(struct dm_cache_policy *p,
- policy_walk_fn fn, void *context)
+static inline uint32_t policy_get_hint(struct dm_cache_policy *p,
+ dm_cblock_t cblock)
{
- return p->walk_mappings ? p->walk_mappings(p, fn, context) : 0;
+ return p->get_hint ? p->get_hint(p, cblock) : 0;
}
static inline int policy_writeback_work(struct dm_cache_policy *p,
diff --git a/drivers/md/dm-cache-policy-smq.c b/drivers/md/dm-cache-policy-smq.c
index cf48a617a3a4..f3cec4e6333c 100644
--- a/drivers/md/dm-cache-policy-smq.c
+++ b/drivers/md/dm-cache-policy-smq.c
@@ -1375,41 +1375,15 @@ static int smq_load_mapping(struct dm_cache_policy *p,
return 0;
}
-static int smq_save_hints(struct smq_policy *mq, struct queue *q,
- policy_walk_fn fn, void *context)
-{
- int r;
- unsigned level;
- struct entry *e;
-
- for (level = 0; level < q->nr_levels; level++)
- for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e)) {
- if (!e->sentinel) {
- r = fn(context, infer_cblock(mq, e),
- e->oblock, e->level);
- if (r)
- return r;
- }
- }
-
- return 0;
-}
-
-static int smq_walk_mappings(struct dm_cache_policy *p, policy_walk_fn fn,
- void *context)
+static uint32_t smq_get_hint(struct dm_cache_policy *p, dm_cblock_t cblock)
{
struct smq_policy *mq = to_smq_policy(p);
- int r = 0;
+ struct entry *e = get_entry(&mq->cache_alloc, from_cblock(cblock));
- /*
- * We don't need to lock here since this method is only called once
- * the IO has stopped.
- */
- r = smq_save_hints(mq, &mq->clean, fn, context);
- if (!r)
- r = smq_save_hints(mq, &mq->dirty, fn, context);
+ if (!e->allocated)
+ return 0;
- return r;
+ return e->level;
}
static void __remove_mapping(struct smq_policy *mq, dm_oblock_t oblock)
@@ -1616,7 +1590,7 @@ static void init_policy_functions(struct smq_policy *mq, bool mimic_mq)
mq->policy.set_dirty = smq_set_dirty;
mq->policy.clear_dirty = smq_clear_dirty;
mq->policy.load_mapping = smq_load_mapping;
- mq->policy.walk_mappings = smq_walk_mappings;
+ mq->policy.get_hint = smq_get_hint;
mq->policy.remove_mapping = smq_remove_mapping;
mq->policy.remove_cblock = smq_remove_cblock;
mq->policy.writeback_work = smq_writeback_work;
diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h
index 05db56eedb6a..aa10b1493f34 100644
--- a/drivers/md/dm-cache-policy.h
+++ b/drivers/md/dm-cache-policy.h
@@ -90,9 +90,6 @@ struct policy_result {
dm_cblock_t cblock; /* POLICY_HIT, POLICY_NEW, POLICY_REPLACE */
};
-typedef int (*policy_walk_fn)(void *context, dm_cblock_t cblock,
- dm_oblock_t oblock, uint32_t hint);
-
/*
* The cache policy object. Just a bunch of methods. It is envisaged that
* this structure will be embedded in a bigger, policy specific structure
@@ -158,8 +155,11 @@ struct dm_cache_policy {
int (*load_mapping)(struct dm_cache_policy *p, dm_oblock_t oblock,
dm_cblock_t cblock, uint32_t hint, bool hint_valid);
- int (*walk_mappings)(struct dm_cache_policy *p, policy_walk_fn fn,
- void *context);
+ /*
+ * Gets the hint for a given cblock. Called in a single threaded
+ * context. So no locking required.
+ */
+ uint32_t (*get_hint)(struct dm_cache_policy *p, dm_cblock_t cblock);
/*
* Override functions used on the error paths of the core target.