Configurable dirty ratio hysteresis

Signed-off-by: Daniel Madej <daniel.madej@huawei.com>

Author: Deixx

inc/cleaning/alru.h

@@ -17,7 +17,8 @@ enum ocf_cleaning_alru_parameters {
 	ocf_alru_stale_buffer_time,
 	ocf_alru_flush_max_buffers,
 	ocf_alru_activity_threshold,
-	ocf_alru_dirty_ratio_trigger,
+	ocf_alru_dirty_ratio_threshold,
+	ocf_alru_dirty_ratio_inertia,
 };
 
 /**
@@ -70,18 +71,29 @@ enum ocf_cleaning_alru_parameters {
 #define OCF_ALRU_DEFAULT_ACTIVITY_THRESHOLD	10000
 
 /**
- * ALRU dirty ratio based cleaning trigger for a cache device
+ * ALRU dirty ratio based cleaning trigger threshold for a cache device
  */
 
-/** Minimum dirty ratio trigger value */
-#define OCF_ALRU_MIN_DIRTY_RATIO_TRIGGER		0
-/** Maximum dirty ratio trigger value */
-#define OCF_ALRU_MAX_DIRTY_RATIO_TRIGGER		100
-/** Default dirty ratio trigger value */
-#define OCF_ALRU_DEFAULT_DIRTY_RATIO_TRIGGER	\
-		OCF_ALRU_MAX_DIRTY_RATIO_TRIGGER
-/** Default dirty ratio trigger inertia */
-#define OCF_ALRU_DEFAULT_TRIGGER_INERTIA		5
+/** Minimum dirty ratio trigger threshold value */
+#define OCF_ALRU_MIN_DIRTY_RATIO_THRESHOLD		0
+/** Maximum dirty ratio trigger threshold value */
+#define OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD		100
+/** Default dirty ratio trigger threshold value */
+#define OCF_ALRU_DEFAULT_DIRTY_RATIO_THRESHOLD	\
+		OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD
+
+/**
+ * ALRU dirty ratio based cleaning trigger inertia for a cache device
+ * Cleaning triggered by exceeding dirty ratio threshold will stop
+ * when dirty ratio drops below (threshold - inertia).
+ */
+
+/** Minimum dirty ratio trigger inertia value */
+#define OCF_ALRU_MIN_DIRTY_RATIO_INERTIA		0
+/** Maximum dirty ratio trigger inertia value */
+#define OCF_ALRU_MAX_DIRTY_RATIO_INERTIA		100
+/** Default dirty ratio trigger inertia value */
+#define OCF_ALRU_DEFAULT_DIRTY_RATIO_INERTIA		5
 /**
  * @}
  */

src/cleaning/alru.c

@@ -363,8 +363,9 @@ void cleaning_policy_alru_setup(struct ocf_cache *cache)
 	config->stale_buffer_time = OCF_ALRU_DEFAULT_STALENESS_TIME;
 	config->flush_max_buffers = OCF_ALRU_DEFAULT_FLUSH_MAX_BUFFERS;
 	config->activity_threshold = OCF_ALRU_DEFAULT_ACTIVITY_THRESHOLD;
-	config->dirty_trigger_threshold = OCF_ALRU_DEFAULT_DIRTY_RATIO_TRIGGER;
-	config->dirty_trigger_inertia = OCF_ALRU_DEFAULT_TRIGGER_INERTIA;
+	config->dirty_trigger_threshold
+		= OCF_ALRU_DEFAULT_DIRTY_RATIO_THRESHOLD;
+	config->dirty_trigger_inertia = OCF_ALRU_DEFAULT_DIRTY_RATIO_INERTIA;
 }
 
 int cleaning_policy_alru_initialize(ocf_cache_t cache, int kick_cleaner)
@@ -632,19 +633,25 @@ int cleaning_policy_alru_set_cleaning_param(ocf_cache_t cache,
 				"activity time threshold: %d\n",
 				config->activity_threshold);
 		break;
-	case ocf_alru_dirty_ratio_trigger:
+	case ocf_alru_dirty_ratio_threshold:
 		OCF_CLEANING_CHECK_PARAM(cache, param_value,
-				OCF_ALRU_MIN_DIRTY_RATIO_TRIGGER,
-				OCF_ALRU_MAX_DIRTY_RATIO_TRIGGER,
+				OCF_ALRU_MIN_DIRTY_RATIO_THRESHOLD,
+				OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD,
 				"dirty_trigger_threshold");
 		config->dirty_trigger_threshold = param_value;
 		ocf_cache_log(cache, log_info, "Write-back flush thread "
 				"dirty ratio trigger threshold: %d\n",
 				config->dirty_trigger_threshold);
-		if (config->dirty_trigger_threshold
-			< config->dirty_trigger_inertia)
-			config->dirty_trigger_inertia
-				= config->dirty_trigger_threshold;
+		break;
+	case ocf_alru_dirty_ratio_inertia:
+		OCF_CLEANING_CHECK_PARAM(cache, param_value,
+				OCF_ALRU_MIN_DIRTY_RATIO_INERTIA,
+				OCF_ALRU_MAX_DIRTY_RATIO_INERTIA,
+				"dirty_trigger_inertia");
+		config->dirty_trigger_inertia = param_value;
+		ocf_cache_log(cache, log_info, "Write-back flush thread "
+				"dirty ratio trigger inertia: %d\n",
+				config->dirty_trigger_inertia);
 		break;
 	default:
 		return -OCF_ERR_INVAL;
@@ -673,9 +680,13 @@ int cleaning_policy_alru_get_cleaning_param(ocf_cache_t cache,
 	case ocf_alru_activity_threshold:
 		*param_value = config->activity_threshold;
 		break;
-	case ocf_alru_dirty_ratio_trigger:
+	case ocf_alru_dirty_ratio_threshold:
 		*param_value = config->dirty_trigger_threshold;
 		break;
+		break;
+	case ocf_alru_dirty_ratio_inertia:
+		*param_value = config->dirty_trigger_inertia;
+		break;
 	default:
 		return -OCF_ERR_INVAL;
 	}
@@ -729,7 +740,8 @@ static bool check_for_dirty_ratio(ocf_cache_t cache,
 	struct alru_context *ctx;
 	uint32_t threshold;
 
-	if (config->dirty_trigger_threshold == OCF_ALRU_MAX_DIRTY_RATIO_TRIGGER)
+	if (config->dirty_trigger_threshold
+			== OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD)
 		return false;
 
 	if (ocf_cache_get_info(cache, &info))