test-mempress: Support unprivileged operation

src/basic/psi-util.c

@@ -10,6 +10,7 @@
 #include "fileio.h"
 #include "parse-util.h"
 #include "psi-util.h"
+#include "string-table.h"
 #include "string-util.h"
 #include "strv.h"
 
@@ -104,6 +105,26 @@ int read_resource_pressure(const char *path, PressureType type, ResourcePressure
         return 0;
 }
 
+const PressureResourceInfo pressure_resource_info[_PRESSURE_RESOURCE_MAX] = {
+        [PRESSURE_MEMORY] = {
+                .name      = "memory",
+                .env_watch = "MEMORY_PRESSURE_WATCH",
+                .env_write = "MEMORY_PRESSURE_WRITE",
+        },
+        [PRESSURE_CPU] = {
+                .name      = "cpu",
+                .env_watch = "CPU_PRESSURE_WATCH",
+                .env_write = "CPU_PRESSURE_WRITE",
+        },
+};
+
+static const char* const pressure_resource_table[_PRESSURE_RESOURCE_MAX] = {
+        [PRESSURE_MEMORY] = "memory",
+        [PRESSURE_CPU]    = "cpu",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(pressure_resource, PressureResource);
+
 int is_pressure_supported(void) {
         static thread_local int cached = -1;
         int r;

src/basic/psi-util.h

@@ -9,6 +9,13 @@ typedef enum PressureType {
         PRESSURE_TYPE_FULL,
 } PressureType;
 
+typedef enum PressureResource {
+        PRESSURE_MEMORY,
+        PRESSURE_CPU,
+        _PRESSURE_RESOURCE_MAX,
+        _PRESSURE_RESOURCE_INVALID = -EINVAL,
+} PressureResource;
+
 /* Averages are stored in fixed-point with 11 bit fractions */
 typedef struct ResourcePressure {
         loadavg_t avg10;
@@ -27,7 +34,18 @@ int read_resource_pressure(const char *path, PressureType type, ResourcePressure
 /* 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)
+/* Metadata for each pressure resource type, for use in sd-event and PID 1 */
+typedef struct PressureResourceInfo {
+        const char *name;       /* "memory", "cpu", "io" */
+        const char *env_watch;  /* "MEMORY_PRESSURE_WATCH", etc. */
+        const char *env_write;  /* "MEMORY_PRESSURE_WRITE", etc. */
+} PressureResourceInfo;
+
+extern const PressureResourceInfo pressure_resource_info[_PRESSURE_RESOURCE_MAX];
+
+DECLARE_STRING_TABLE_LOOKUP(pressure_resource, PressureResource);
+
+/* Default parameters for pressure watch logic in sd-event and PID 1 */
+#define PRESSURE_DEFAULT_TYPE "some"
+#define PRESSURE_DEFAULT_THRESHOLD_USEC (200 * USEC_PER_MSEC)
+#define PRESSURE_DEFAULT_WINDOW_USEC (2 * USEC_PER_SEC)