mm/damon/core: implement PSI metric DAMOS quota goal

Extend DAMOS quota goal metric with system wide memory pressure stall
time.  Specifically, the system level 'some' PSI for memory is used.  The
target value can be set in microseconds.  DAMOS measures the increased
amount of the PSI metric in last quota_reset_interval and use the ratio of
it versus the user-specified target PSI value as the score for the
auto-tuning feedback loop.

Link: https://lkml.kernel.org/r/20240219194431.159606-14-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 973423166ee28f..6d503c1c125ef0 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -11,6 +11,7 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/mm.h>
+#include <linux/psi.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
@@ -1125,6 +1126,25 @@ static unsigned long damon_feed_loop_next_input(unsigned long last_input,
 	return min_input;
 }
 
+#ifdef CONFIG_PSI
+
+static u64 damos_get_some_mem_psi_total(void)
+{
+	if (static_branch_likely(&psi_disabled))
+		return 0;
+	return div_u64(psi_system.total[PSI_AVGS][PSI_MEM * 2],
+			NSEC_PER_USEC);
+}
+
+#else	/* CONFIG_PSI */
+
+static inline u64 damos_get_some_mem_psi_total(void)
+{
+	return 0;
+};
+
+#endif	/* CONFIG_PSI */
+
 static void damos_set_quota_goal_current_value(struct damos_quota_goal *goal)
 {
 	u64 now_psi_total;
@@ -1133,6 +1153,11 @@ static void damos_set_quota_goal_current_value(struct damos_quota_goal *goal)
 	case DAMOS_QUOTA_USER_INPUT:
 		/* User should already set goal->current_value */
 		break;
+	case DAMOS_QUOTA_SOME_MEM_PSI_US:
+		now_psi_total = damos_get_some_mem_psi_total();
+		goal->current_value = now_psi_total - goal->last_psi_total;
+		goal->last_psi_total = now_psi_total;
+		break;
 	default:
 		break;
 	}