1 files changed, 165 insertions, 5 deletions

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 36dcd881a1..786b06239c 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -31,7 +31,7 @@ static struct damon_sysfs_scheme_region *damon_sysfs_scheme_region_alloc(
 		return NULL;
 	sysfs_region->kobj = (struct kobject){};
 	sysfs_region->ar = region->ar;
-	sysfs_region->nr_accesses = region->nr_accesses;
+	sysfs_region->nr_accesses = region->nr_accesses_bp / 10000;
 	sysfs_region->age = region->age;
 	INIT_LIST_HEAD(&sysfs_region->list);
 	return sysfs_region;
@@ -113,11 +113,55 @@ static const struct kobj_type damon_sysfs_scheme_region_ktype = {
  * scheme regions directory
  */
 
+/*
+ * enum damos_sysfs_regions_upd_status - Represent DAMOS tried regions update
+ *					 status
+ * @DAMOS_TRIED_REGIONS_UPD_IDLE:		Waiting for next request.
+ * @DAMOS_TRIED_REGIONS_UPD_STARTED:		Update started.
+ * @DAMOS_TRIED_REGIONS_UPD_FINISHED:	Update finished.
+ *
+ * Each DAMON-based operation scheme (&struct damos) has its own apply
+ * interval, and we need to expose the scheme tried regions based on only
+ * single snapshot.  For this, we keep the tried regions update status for each
+ * scheme.  The status becomes 'idle' at the beginning.
+ *
+ * Once the tried regions update request is received, the request handling
+ * start function (damon_sysfs_scheme_update_regions_start()) sets the status
+ * of all schemes as 'idle' again, and register ->before_damos_apply() and
+ * ->after_sampling() callbacks.
+ *
+ * Then, the first followup ->before_damos_apply() callback
+ * (damon_sysfs_before_damos_apply()) sets the status 'started'.  The first
+ * ->after_sampling() callback (damon_sysfs_after_sampling()) after the call
+ * is called only after the scheme is completely applied
+ * to the given snapshot.  Hence the callback knows the situation by showing
+ * 'started' status, and sets the status as 'finished'.  Then,
+ * damon_sysfs_before_damos_apply() understands the situation by showing the
+ * 'finished' status and do nothing.
+ *
+ * If DAMOS is not applied to any region due to any reasons including the
+ * access pattern, the watermarks, the quotas, and the filters,
+ * ->before_damos_apply() will not be called back.  Until the situation is
+ * changed, the update will not be finished.  To avoid this,
+ * damon_sysfs_after_sampling() set the status as 'finished' if more than two
+ * apply intervals of the scheme is passed while the state is 'idle'.
+ *
+ *  Finally, the tried regions request handling finisher function
+ *  (damon_sysfs_schemes_update_regions_stop()) unregisters the callbacks.
+ */
+enum damos_sysfs_regions_upd_status {
+	DAMOS_TRIED_REGIONS_UPD_IDLE,
+	DAMOS_TRIED_REGIONS_UPD_STARTED,
+	DAMOS_TRIED_REGIONS_UPD_FINISHED,
+};
+
 struct damon_sysfs_scheme_regions {
 	struct kobject kobj;
 	struct list_head regions_list;
 	int nr_regions;
 	unsigned long total_bytes;
+	enum damos_sysfs_regions_upd_status upd_status;
+	unsigned long upd_timeout_jiffies;
 };
 
 static struct damon_sysfs_scheme_regions *
@@ -133,6 +177,7 @@ damon_sysfs_scheme_regions_alloc(void)
 	INIT_LIST_HEAD(&regions->regions_list);
 	regions->nr_regions = 0;
 	regions->total_bytes = 0;
+	regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE;
 	return regions;
 }
 
@@ -1124,6 +1169,7 @@ struct damon_sysfs_scheme {
 	struct kobject kobj;
 	enum damos_action action;
 	struct damon_sysfs_access_pattern *access_pattern;
+	unsigned long apply_interval_us;
 	struct damon_sysfs_quotas *quotas;
 	struct damon_sysfs_watermarks *watermarks;
 	struct damon_sysfs_scheme_filters *filters;
@@ -1144,7 +1190,7 @@ static const char * const damon_sysfs_damos_action_strs[] = {
 };
 
 static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
-		enum damos_action action)
+		enum damos_action action, unsigned long apply_interval_us)
 {
 	struct damon_sysfs_scheme *scheme = kmalloc(sizeof(*scheme),
 				GFP_KERNEL);
@@ -1153,6 +1199,7 @@ static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
 		return NULL;
 	scheme->kobj = (struct kobject){};
 	scheme->action = action;
+	scheme->apply_interval_us = apply_interval_us;
 	return scheme;
 }
 
@@ -1356,6 +1403,25 @@ static ssize_t action_store(struct kobject *kobj, struct kobj_attribute *attr,
 	return -EINVAL;
 }
 
+static ssize_t apply_interval_us_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme *scheme = container_of(kobj,
+			struct damon_sysfs_scheme, kobj);
+
+	return sysfs_emit(buf, "%lu\n", scheme->apply_interval_us);
+}
+
+static ssize_t apply_interval_us_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme *scheme = container_of(kobj,
+			struct damon_sysfs_scheme, kobj);
+	int err = kstrtoul(buf, 0, &scheme->apply_interval_us);
+
+	return err ? err : count;
+}
+
 static void damon_sysfs_scheme_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_scheme, kobj));
@@ -1364,8 +1430,12 @@ static void damon_sysfs_scheme_release(struct kobject *kobj)
 static struct kobj_attribute damon_sysfs_scheme_action_attr =
 		__ATTR_RW_MODE(action, 0600);
 
+static struct kobj_attribute damon_sysfs_scheme_apply_interval_us_attr =
+		__ATTR_RW_MODE(apply_interval_us, 0600);
+
 static struct attribute *damon_sysfs_scheme_attrs[] = {
 	&damon_sysfs_scheme_action_attr.attr,
+	&damon_sysfs_scheme_apply_interval_us_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_scheme);
@@ -1416,7 +1486,11 @@ static int damon_sysfs_schemes_add_dirs(struct damon_sysfs_schemes *schemes,
 	schemes->schemes_arr = schemes_arr;
 
 	for (i = 0; i < nr_schemes; i++) {
-		scheme = damon_sysfs_scheme_alloc(DAMOS_STAT);
+		/*
+		 * apply_interval_us as 0 means same to aggregation interval
+		 * (same to before-apply_interval behavior)
+		 */
+		scheme = damon_sysfs_scheme_alloc(DAMOS_STAT, 0);
 		if (!scheme) {
 			damon_sysfs_schemes_rm_dirs(schemes);
 			return -ENOMEM;
@@ -1613,8 +1687,8 @@ static struct damos *damon_sysfs_mk_scheme(
 		.low = sysfs_wmarks->low,
 	};
 
-	scheme = damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
-			&wmarks);
+	scheme = damon_new_scheme(&pattern, sysfs_scheme->action,
+			sysfs_scheme->apply_interval_us, &quota, &wmarks);
 	if (!scheme)
 		return NULL;
 
@@ -1644,6 +1718,7 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	scheme->pattern.max_age_region = access_pattern->age->max;
 
 	scheme->action = sysfs_scheme->action;
+	scheme->apply_interval_us = sysfs_scheme->apply_interval_us;
 
 	scheme->quota.ms = sysfs_quotas->ms;
 	scheme->quota.sz = sysfs_quotas->sz;
@@ -1750,6 +1825,10 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
 		return 0;
 
 	sysfs_regions = sysfs_schemes->schemes_arr[schemes_idx]->tried_regions;
+	if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_FINISHED)
+		return 0;
+	if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_IDLE)
+		sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_STARTED;
 	sysfs_regions->total_bytes += r->ar.end - r->ar.start;
 	if (damos_regions_upd_total_bytes_only)
 		return 0;
@@ -1768,6 +1847,31 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
 	return 0;
 }
 
+/*
+ * DAMON callback that called after each accesses sampling.  While this
+ * callback is registered, damon_sysfs_lock should be held to ensure the
+ * regions directories exist.
+ */
+static int damon_sysfs_after_sampling(struct damon_ctx *ctx)
+{
+	struct damon_sysfs_schemes *sysfs_schemes =
+		damon_sysfs_schemes_for_damos_callback;
+	struct damon_sysfs_scheme_regions *sysfs_regions;
+	int i;
+
+	for (i = 0; i < sysfs_schemes->nr; i++) {
+		sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
+		if (sysfs_regions->upd_status ==
+				DAMOS_TRIED_REGIONS_UPD_STARTED ||
+				time_after(jiffies,
+					sysfs_regions->upd_timeout_jiffies))
+			sysfs_regions->upd_status =
+				DAMOS_TRIED_REGIONS_UPD_FINISHED;
+	}
+
+	return 0;
+}
+
 /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
 int damon_sysfs_schemes_clear_regions(
 		struct damon_sysfs_schemes *sysfs_schemes,
@@ -1791,6 +1895,43 @@ int damon_sysfs_schemes_clear_regions(
 	return 0;
 }
 
+static struct damos *damos_sysfs_nth_scheme(int n, struct damon_ctx *ctx)
+{
+	struct damos *scheme;
+	int i = 0;
+
+	damon_for_each_scheme(scheme, ctx) {
+		if (i == n)
+			return scheme;
+		i++;
+	}
+	return NULL;
+}
+
+static void damos_tried_regions_init_upd_status(
+		struct damon_sysfs_schemes *sysfs_schemes,
+		struct damon_ctx *ctx)
+{
+	int i;
+	struct damos *scheme;
+	struct damon_sysfs_scheme_regions *sysfs_regions;
+
+	for (i = 0; i < sysfs_schemes->nr; i++) {
+		sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
+		scheme = damos_sysfs_nth_scheme(i, ctx);
+		if (!scheme) {
+			sysfs_regions->upd_status =
+				DAMOS_TRIED_REGIONS_UPD_FINISHED;
+			continue;
+		}
+		sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE;
+		sysfs_regions->upd_timeout_jiffies = jiffies +
+			2 * usecs_to_jiffies(scheme->apply_interval_us ?
+					scheme->apply_interval_us :
+					ctx->attrs.aggr_interval);
+	}
+}
+
 /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
 int damon_sysfs_schemes_update_regions_start(
 		struct damon_sysfs_schemes *sysfs_schemes,
@@ -1798,11 +1939,29 @@ int damon_sysfs_schemes_update_regions_start(
 {
 	damon_sysfs_schemes_clear_regions(sysfs_schemes, ctx);
 	damon_sysfs_schemes_for_damos_callback = sysfs_schemes;
+	damos_tried_regions_init_upd_status(sysfs_schemes, ctx);
 	damos_regions_upd_total_bytes_only = total_bytes_only;
 	ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply;
+	ctx->callback.after_sampling = damon_sysfs_after_sampling;
 	return 0;
 }
 
+bool damos_sysfs_regions_upd_done(void)
+{
+	struct damon_sysfs_schemes *sysfs_schemes =
+		damon_sysfs_schemes_for_damos_callback;
+	struct damon_sysfs_scheme_regions *sysfs_regions;
+	int i;
+
+	for (i = 0; i < sysfs_schemes->nr; i++) {
+		sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
+		if (sysfs_regions->upd_status !=
+				DAMOS_TRIED_REGIONS_UPD_FINISHED)
+			return false;
+	}
+	return true;
+}
+
 /*
  * Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock.  Caller
  * should unlock damon_sysfs_lock which held before
@@ -1812,6 +1971,7 @@ int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx)
 {
 	damon_sysfs_schemes_for_damos_callback = NULL;
 	ctx->callback.before_damos_apply = NULL;
+	ctx->callback.after_sampling = NULL;
 	damon_sysfs_schemes_region_idx = 0;
 	return 0;
 }