mm/damon/core: add DAMOS quota gaol metric for per-memcg per-numa free memory

Add a variant of DAMOS_QUOTA_NODE_MEMCG_USED_BP, for the free memory
portion.  The value of the metric is implemented as the entire memory of
the given NUMA node subtracted by the given cgroup's usage.  So from a
perspective, "unused" could be a better term than "free".  But arguably it
is not very clear what is better, so use the term "free".

Link: https://lkml.kernel.org/r/20251017212706.183502-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 0d63ceb7e6ef27995d03c5fd0c56e5dc4bc4ae37..0edf41d36ea1f854bfaef7d2c53c901b895b111c 100644 (file)
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -148,6 +148,7 @@ enum damos_action {
  * @DAMOS_QUOTA_NODE_MEM_USED_BP:      MemUsed ratio of a node.
  * @DAMOS_QUOTA_NODE_MEM_FREE_BP:      MemFree ratio of a node.
  * @DAMOS_QUOTA_NODE_MEMCG_USED_BP:    MemUsed ratio of a node for a cgroup.
+ * @DAMOS_QUOTA_NODE_MEMCG_FREE_BP:    MemFree ratio of a node for a cgroup.
  * @NR_DAMOS_QUOTA_GOAL_METRICS:       Number of DAMOS quota goal metrics.
  *
  * Metrics equal to larger than @NR_DAMOS_QUOTA_GOAL_METRICS are unsupported.
@@ -158,6 +159,7 @@ enum damos_quota_goal_metric {
        DAMOS_QUOTA_NODE_MEM_USED_BP,
        DAMOS_QUOTA_NODE_MEM_FREE_BP,
        DAMOS_QUOTA_NODE_MEMCG_USED_BP,
+       DAMOS_QUOTA_NODE_MEMCG_FREE_BP,
        NR_DAMOS_QUOTA_GOAL_METRICS,
 };
 
@@ -183,8 +185,8 @@ enum damos_quota_goal_metric {
  * If @metric is DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP, @nid represents the node
  * id of the target node to account the used/free memory.
  *
- * If @metric is DAMOS_QUOTA_NODE_MEMCG_USED_BP, @nid and @memcg_id represents
- * the node id and the cgroup to account the used memory for.
+ * If @metric is DAMOS_QUOTA_NODE_MEMCG_{USED,FREE}_BP, @nid and @memcg_id
+ * represents the node id and the cgroup to account the used memory for.
  */
 struct damos_quota_goal {
        enum damos_quota_goal_metric metric;

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 8aa8d269df9070f1348a5bc871af288157fac29a..a9c11d2d37b076a48469fc922b14303178428017 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -790,6 +790,7 @@ static void damos_commit_quota_goal_union(
                dst->nid = src->nid;
                break;
        case DAMOS_QUOTA_NODE_MEMCG_USED_BP:
+       case DAMOS_QUOTA_NODE_MEMCG_FREE_BP:
                dst->nid = src->nid;
                dst->memcg_id = src->memcg_id;
                break;
@@ -2046,7 +2047,7 @@ static unsigned long damos_get_node_memcg_used_bp(
 {
        struct mem_cgroup *memcg;
        struct lruvec *lruvec;
-       unsigned long used_pages;
+       unsigned long used_pages, numerator;
        struct sysinfo i;
 
        rcu_read_lock();
@@ -2066,7 +2067,11 @@ static unsigned long damos_get_node_memcg_used_bp(
        used_pages += lruvec_page_state(lruvec, NR_INACTIVE_FILE);
 
        si_meminfo_node(&i, goal->nid);
-       return used_pages * 10000 / i.totalram;
+       if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP)
+               numerator = used_pages;
+       else    /* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */
+               numerator = i.totalram - used_pages;
+       return numerator * 10000 / i.totalram;
 }
 #else
 static __kernel_ulong_t damos_get_node_mem_bp(
@@ -2101,6 +2106,7 @@ static void damos_set_quota_goal_current_value(struct damos_quota_goal *goal)
                goal->current_value = damos_get_node_mem_bp(goal);
                break;
        case DAMOS_QUOTA_NODE_MEMCG_USED_BP:
+       case DAMOS_QUOTA_NODE_MEMCG_FREE_BP:
                goal->current_value = damos_get_node_memcg_used_bp(goal);
                break;
        default: