From e8f05481ea1f5323b64f177d57f0f34cb0cdbee5 Mon Sep 17 00:00:00 2001 From: Andreas Eversberg Date: Wed, 24 Jan 2024 17:12:27 +0100 Subject: [PATCH] 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 --- src/core/timer.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/src/core/timer.c b/src/core/timer.c index 20d87a059..067bd8758 100644 --- a/src/core/timer.c +++ b/src/core/timer.c @@ -191,7 +191,16 @@ int osmo_timers_nearest_ms(void) 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; }