More psi-monitor info

psi-monitor/Makefile.am

@@ -1,3 +1,5 @@
+AM_CFLAGS = -Wall -Werror
+
 sbin_PROGRAMS = psi-monitor
 psi_monitor_SOURCES = psi-monitor.c
 

psi-monitor/psi-monitor.c

@@ -7,8 +7,7 @@
 #include <err.h>
 #include <unistd.h>
 #include <string.h>
-
-#define DEBUG false
+#include <getopt.h>
 
 /* Daemon parameters */
 #define POLL_INTERVAL       5
@@ -19,6 +18,23 @@
 #define PSI_MEMORY_FILE     "/proc/pressure/memory"
 #define BUFSIZE             256
 
+static bool opt_debug = false;
+static const char *short_options = "dh";
+static struct option long_options[] = {
+    {"debug", 0, 0, 'd'},
+    {"help", 0, 0, 'h'},
+    {0, 0, 0, 0}
+};
+
+static void usage(const char *progname) {
+    printf("Usage: %s [OPTION]...\n"
+           "Invoke out of memory killer on excessive memory pressure.\n"
+           "\n"
+           "  -d, --debug\tprint debugging messages\n"
+           "  -h, --help\tdisplay this help and exit\n",
+           progname);
+}
+
 static ssize_t fstr(const char *path, char *rbuf, const char *wbuf) {
     int fd;
     ssize_t n;
@@ -46,12 +62,28 @@ static ssize_t fstr(const char *path, char *rbuf, const char *wbuf) {
 }
 
 static void sysrq_trigger_oom() {
-    printf("Above threshold limit, killing task and pausing for recovery\n");
     fstr(SYSRQ_TRIGGER_FILE, NULL, "f");
     sleep(RECOVERY_INTERVAL);
 }
 
 int main(int argc, char **argv) {
+    while (true) {
+        int c = getopt_long(argc, argv, short_options, long_options, NULL);
+        if (c == -1)
+            break;
+
+        switch (c) {
+        case 'd':
+            opt_debug = true;
+            break;
+        case 'h':
+            usage(argv[0]);
+            return 0;
+        default:
+            return 1;
+        }
+    }
+
     setvbuf(stdout, NULL, _IOLBF, 0);
     printf("poll_interval=%ds, recovery_interval=%ds, stall_threshold=%d%%\n",
            POLL_INTERVAL, RECOVERY_INTERVAL, MEM_THRESHOLD);
@@ -68,12 +100,16 @@ int main(int argc, char **argv) {
         i+=11; /* skip "full avg10=" */
 
         sscanf(buf+i, "%f", &full_avg10);
-        if (DEBUG) printf("full_avg10=%f\n", full_avg10);
+        if (opt_debug) printf("full_avg10=%f\n", full_avg10);
 
-        if (full_avg10 > MEM_THRESHOLD)
+        if (full_avg10 > MEM_THRESHOLD) {
+            printf("Memory pressure %.1f%% above threshold limit %d%%, "
+                   "killing task and pausing %d seconds for recovery\n",
+                   full_avg10, MEM_THRESHOLD, RECOVERY_INTERVAL);
             sysrq_trigger_oom();
-        else
+        } else {
             sleep(POLL_INTERVAL);
+        }
     }
 
     return 0;