1 files changed, 35 insertions, 0 deletions
diff --git a/src/basic/psi-util.h b/src/basic/psi-util.h
new file mode 100644
index 0000000..bf8f4fe
--- /dev/null
+++ b/src/basic/psi-util.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "parse-util.h"
+#include "time-util.h"
+
+typedef enum PressureType {
+        PRESSURE_TYPE_SOME,
+        PRESSURE_TYPE_FULL,
+} PressureType;
+
+/* Averages are stored in fixed-point with 11 bit fractions */
+typedef struct ResourcePressure {
+        loadavg_t avg10;
+        loadavg_t avg60;
+        loadavg_t avg300;
+        usec_t total;
+} ResourcePressure;
+
+/** Upstream 4.20+ format
+ *
+ *  some avg10=0.22 avg60=0.17 avg300=1.11 total=58761459
+ *  full avg10=0.23 avg60=0.16 avg300=1.08 total=58464525
+ */
+int read_resource_pressure(const char *path, PressureType type, ResourcePressure *ret);
+
+/* Was the kernel compiled with CONFIG_PSI=y? 1 if yes, 0 if not, negative on error. */
+int is_pressure_supported(void);
+
+/* Default parameters for memory pressure watch logic in sd-event and PID 1 */
+#define MEMORY_PRESSURE_DEFAULT_TYPE "some"
+#define MEMORY_PRESSURE_DEFAULT_THRESHOLD_USEC (200 * USEC_PER_MSEC)
+#define MEMORY_PRESSURE_DEFAULT_WINDOW_USEC (2 * USEC_PER_SEC)