Configurable dirty ratio hysteresis

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

Author: Deixx

inc/cleaning/alru.h

@@ -18,6 +18,7 @@ enum ocf_cleaning_alru_parameters {
 	ocf_alru_flush_max_buffers,
 	ocf_alru_activity_threshold,
 	ocf_alru_dirty_ratio_threshold,
+	ocf_alru_dirty_ratio_inertia,
 };
 
 /**
@@ -70,17 +71,28 @@ 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 threshold value */
+/** Minimum dirty ratio trigger threshold value */
 #define OCF_ALRU_MIN_DIRTY_RATIO_THRESHOLD		0
-/** Maximum dirty ratio threshold value */
+/** Maximum dirty ratio trigger threshold value */
 #define OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD		100
-/** Default dirty ratio threshold value */
+/** Default dirty ratio trigger threshold value */
 #define OCF_ALRU_DEFAULT_DIRTY_RATIO_THRESHOLD	\
 		OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD
-/** Default dirty ratio threshold inertia */
+
+/**
+ * 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

@@ -775,6 +775,16 @@ int cleaning_policy_alru_set_cleaning_param(ocf_cache_t cache,
 				"dirty ratio trigger threshold: %d\n",
 				config->dirty_ratio_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_ratio_inertia");
+		config->dirty_ratio_inertia = param_value;
+		ocf_cache_log(cache, log_info, "Write-back flush thread "
+				"dirty ratio trigger inertia: %d\n",
+				config->dirty_ratio_inertia);
+		break;
 	default:
 		return -OCF_ERR_INVAL;
 	}
@@ -805,6 +815,9 @@ int cleaning_policy_alru_get_cleaning_param(ocf_cache_t cache,
 	case ocf_alru_dirty_ratio_threshold:
 		*param_value = config->dirty_ratio_threshold;
 		break;
+	case ocf_alru_dirty_ratio_inertia:
+		*param_value = config->dirty_ratio_inertia;
+		break;
 	default:
 		return -OCF_ERR_INVAL;
 	}
@@ -858,7 +871,8 @@ static bool check_for_dirty_ratio(ocf_cache_t cache,
 	struct alru_context *ctx;
 	uint32_t threshold;
 
-	if (config->dirty_ratio_threshold == OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD)
+	if (config->dirty_ratio_threshold
+			== OCF_ALRU_MAX_DIRTY_RATIO_THRESHOLD)
 		return false;
 
 	if (ocf_cache_get_info(cache, &info))