diff --git a/README.md b/README.md
index 2c895b3..fb37fe7 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,15 @@
 # mxq
 MXQ - mariux64 job scheduling system
 
+## Sources
+### Main git repository
+
+https://github.molgen.mpg.de/mariux64/mxq
+
+### github.com clone
+
+https://github.com/mariux/mxq
+
 ## Installation
 ### Install using `GNU make`
 ```
diff --git a/mx_util.h b/mx_util.h
index 16a27d3..508476c 100644
--- a/mx_util.h
+++ b/mx_util.h
@@ -7,6 +7,8 @@
 #include <string.h>
 #include <stdio.h>
 #include <sched.h>
+#include <unistd.h>
+#include <sys/time.h>
 
 #include "mx_log.h"
 
@@ -71,6 +73,18 @@ static inline void __mx_fclose(FILE **ptr) {
 #undef mx_streq_nocase
 #define mx_streq_nocase(a, b) (strcasecmp((a), (b)) == 0)
 
+#define mx_within_rate_limit_or_return(sec, ret) \
+  do {\
+    static struct timeval _sleep = {0};\
+    struct timeval _now;\
+    struct timeval _delta;\
+    gettimeofday(&_now, NULL);\
+    timersub(&_now, &_sleep, &_delta);\
+    if (_delta.tv_sec < (sec))\
+        return (ret);\
+    _sleep = _now;\
+  } while(0)
+
 int mx_strbeginswith(char *str, const char *start, char **endptr);
 int mx_stribeginswith(char *str, const char *start, char **endptr);
 int mx_strbeginswithany(char *str, char **starts, char **endptr);
diff --git a/mxqd.c b/mxqd.c
index 77706c7..09b8c5b 100644
--- a/mxqd.c
+++ b/mxqd.c
@@ -1512,6 +1512,11 @@ int killall_over_time(struct mxq_server *server)
 
     assert(server);
 
+    /* limit killing to every >= 5 minutes */
+    mx_within_rate_limit_or_return(5*60, 1);
+
+    mx_log_info("killall_over_time: Sending signals to all jobs running longer than requested.");
+
     gettimeofday(&now, NULL);
 
     for (user=server->users; user; user=user->next) {
@@ -1909,7 +1914,6 @@ int main(int argc, char *argv[])
         killallcancelled(&server, SIGTERM, 0);
         killallcancelled(&server, SIGINT, 0);
         killall_over_time(&server);
-        killall_over_time(&server);
 
         mx_log_info("jobs_running=%lu global_sigint_cnt=%d global_sigterm_cnt=%d : Exiting. Wating for jobs to finish. Sleeping for a while.",
               server.jobs_running, global_sigint_cnt, global_sigterm_cnt);