Add memory check before engaging promotion policy

Signed-off-by: Jan Musial <jan.musial@intel.com>

src/promotion/nhit/nhit.c

@@ -27,10 +27,35 @@ void nhit_setup(ocf_cache_t cache)
 	cfg->trigger_threshold = OCF_NHIT_TRIGGER_DEFAULT;
 }
 
+static uint64_t nhit_sizeof(ocf_cache_t cache)
+{
+	uint64_t size = 0;
+
+	size += sizeof(struct nhit_policy_context);
+	size += nhit_hash_sizeof(ocf_metadata_get_cachelines_count(cache) *
+			NHIT_MAPPING_RATIO);
+
+	return size;
+}
+
 ocf_error_t nhit_init(ocf_cache_t cache)
 {
 	struct nhit_policy_context *ctx;
 	int result = 0;
+	uint64_t available, size;
+
+	size = nhit_sizeof(cache);
+	available = env_get_free_memory();
+
+	if (size >= available) {
+		ocf_cache_log(cache, log_err, "Not enough memory to "
+				"initialize 'nhit' promotion policy! "
+				"Required %lu, available %lu\n",
+				(long unsigned)size,
+				(long unsigned)available);
+
+		return -OCF_ERR_NO_FREE_RAM;
+	}
 
 	ctx = env_vmalloc(sizeof(*ctx));
 	if (!ctx) {

src/promotion/nhit/nhit_hash.c

@@ -107,6 +107,26 @@ struct nhit_hash {
 	env_spinlock rb_pointer_lock;
 };
 
+static uint64_t calculate_hash_buckets(uint64_t hash_size)
+{
+	return OCF_DIV_ROUND_UP(hash_size / 4, HASH_PRIME) * HASH_PRIME - 1;
+}
+
+uint64_t nhit_hash_sizeof(uint64_t hash_size)
+{
+	uint64_t size = 0;
+	uint64_t n_buckets = calculate_hash_buckets(hash_size);
+
+	size += sizeof(struct nhit_hash);
+
+	size += n_buckets * sizeof(ocf_cache_line_t);
+	size += n_buckets * sizeof(env_rwsem);
+
+	size += hash_size * sizeof(struct nhit_list_elem);
+
+	return size;
+}
+
 ocf_error_t nhit_hash_init(uint64_t hash_size, nhit_hash_t *ctx)
 {
 	int result = 0;
@@ -121,9 +141,7 @@ ocf_error_t nhit_hash_init(uint64_t hash_size, nhit_hash_t *ctx)
 	}
 
 	new_ctx->rb_entries = hash_size;
-	new_ctx->hash_entries = OCF_DIV_ROUND_UP(
-			new_ctx->rb_entries / 4,
-			HASH_PRIME) * HASH_PRIME - 1;
+	new_ctx->hash_entries = calculate_hash_buckets(hash_size);
 
 	new_ctx->hash_map = env_vzalloc(
 			new_ctx->hash_entries * sizeof(*new_ctx->hash_map));

src/promotion/nhit/nhit_hash.h

@@ -10,6 +10,8 @@
 
 typedef struct nhit_hash *nhit_hash_t;
 
+uint64_t nhit_hash_sizeof(uint64_t hash_size);
+
 ocf_error_t nhit_hash_init(uint64_t hash_size, nhit_hash_t *ctx);
 
 void nhit_hash_deinit(nhit_hash_t ctx);

src/promotion/promotion.c

@@ -48,6 +48,13 @@ ocf_error_t ocf_promotion_init(ocf_cache_t cache, ocf_promotion_t type)
 	if (result) {
 		env_vfree(cache->promotion_policy);
 		cache->promotion_policy = NULL;
+		ocf_cache_log(cache, log_info,
+				"Policy '%s' failed to initialize\n",
+				ocf_promotion_policies[type].name);
+	} else {
+		ocf_cache_log(cache, log_info,
+				"Policy '%s' initialized successfully\n",
+				ocf_promotion_policies[type].name);
 	}
 
 	return result;
@@ -99,6 +106,10 @@ ocf_error_t ocf_promotion_set_policy(ocf_promotion_policy_t policy,
 				"Falling back to 'always' promotion policy\n");
 		cache->conf_meta->promotion_policy_type = ocf_promotion_always;
 		policy->type = ocf_promotion_always;
+	} else {
+		ocf_cache_log(cache, log_info,
+				"Switched to '%s' promotion policy\n",
+				ocf_promotion_policies[type].name);
 	}
 
 	return result;