rtspin: add -T (use clock_nanosleep) option

This make rtspin use the regular Linux API for periodic activations
instead of the LITMUS^RT-specifc sleep_next_period() API.

1 files changed, 23 insertions, 2 deletions

diff --git a/bin/rtspin.c b/bin/rtspin.c
index d33e9b3..498603f 100644
--- a/bin/rtspin.c
+++ b/bin/rtspin.c
@@ -62,6 +62,8 @@ const char *usage_msg =
         "                      default w/o -S: periodic job releases\n"
         "                      default if FILE is omitted: read from STDIN\n"
         "\n"
+        "    -T                use clock_nanosleep() instead of sleep_next_period()\n"
+        "\n"
         "    -X PROTOCOL       access a shared resource protected by a locking protocol\n"
         "    -L CS-LENGTH      simulate a critical section length of CS-LENGTH milliseconds\n"
         "    -Q RESOURCE-ID    access the resource identified by RESOURCE-ID\n"
@@ -276,7 +278,7 @@ static void job(double exec_time, double program_end, int lock_od, double cs_len
         }
 }
 
-#define OPTSTR "p:c:wlveo:F:s:m:q:r:X:L:Q:iRu:Bhd:C:S::"
+#define OPTSTR "p:c:wlveo:F:s:m:q:r:X:L:Q:iRu:Bhd:C:S::T"
 int main(int argc, char** argv)
 {
         int ret;
@@ -310,6 +312,9 @@ int main(int argc, char** argv)
         int sporadic = 0;  /* trigger jobs sporadically? */
         int event_fd = -1; /* file descriptor for sporadic events */
 
+        int linux_sleep = 0; /* use Linux API for periodic activations? */
+        lt_t next_release;
+
         int verbose = 0;
         unsigned int job_no;
         struct control_page* cp;
@@ -379,6 +384,9 @@ int main(int argc, char** argv)
                                       "for STDIN.");
                         }
                         break;
+                case 'T':
+                        linux_sleep = 1;
+                        break;
                 case 'm':
                         nr_of_pages = atoi(optarg);
                         break;
@@ -576,6 +584,10 @@ int main(int argc, char** argv)
                 start = wctime();
         }
 
+        if (cp)
+                next_release = cp->release + period;
+        else
+                next_release = litmus_clock() + period;
 
         /* main job loop */
         cur_job = 0;
@@ -645,7 +657,16 @@ int main(int argc, char** argv)
                 /* wait for periodic job activation (unless sporadic) */
                 if (!sporadic) {
                         /* periodic job activations */
-                        sleep_next_period();
+                        if (linux_sleep) {
+                                /* Use vanilla Linux API. This looks to the
+                                 * active LITMUS^RT plugin like a
+                                 * self-suspension. */
+                                lt_sleep_until(next_release);
+                                next_release += period;
+                        } else
+                                /* Use LITMUS^RT API: some plugins optimize
+                                 * this by not actually suspending the task. */
+                                sleep_next_period();
                 }
         }