Prevent poll() in select.c to timeout too early
Adjust osmo_timers_nearest_ms() to round up the remaining time.
Note that poll() has a granularity of 1 millisecond.
Previously, when rounding down the remaining time, osmo_select_main()
would return too early, before the nearest timer timed out.
Consequently, the main loop repeatedly called osmo_select_main() until
the timer actually timed out, resulting in excessive CPU usage.
By modifying osmo_timers_nearest_ms() to round up the remaining time,
we ensure accurate timeout calculations, preventing unnecessary CPU
consumption during the main loop.
The patch only applies to non-embedded version of libosmocore, because
the impact on embedded systems is not verified tested.
Related: OS#6339
Change-Id: I79de77c79af4d50d1eb9ca0c5417123ff760dca3
diff --git a/src/core/timer.c b/src/core/timer.c
index 20d87a0..067bd87 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -191,7 +191,16 @@
return -1;
nearest_ms = nearest_p->tv_sec * 1000;
+#ifndef EMBEDDED
+ /* By adding 999 milliseconds, we ensure rounding up to the nearest
+ * whole millisecond. This approach prevents the return of 0 when the
+ * timer is still active, and it guarantees that the calling process
+ * does not wait for a duration shorter than the time remaining on the
+ * timer. */
+ nearest_ms += (nearest_p->tv_usec + 999) / 1000;
+#else
nearest_ms += nearest_p->tv_usec / 1000;
+#endif
return nearest_ms;
}