At the calculation of the first FPS, gears has initialized last FPS time with gettimeofday(). But the callback_data passed in the callback of wl_surface_frame() is the current time, in milliseconds, with an undefined base. Because of this subtracting last FPS time from callback_data makes no sense. For example, below is the result of running weston-gears on weston with drm backend:
$ weston-gears Warning: FPS count is limited by the wayland compositor or monitor refresh rate 1 frames in 1094460.125 seconds = 0.000 FPS 301 frames in 5.016 seconds = 60.008 FPS 301 frames in 5.016 seconds = 60.008 FPS 301 frames in 5.016 seconds = 60.008 FPS As you can see, the the first FPS value is something odd. This patch fixes it by initializing last FPS time with the callback_data passed in the first callback. --- clients/gears.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/clients/gears.c b/clients/gears.c index 95f0bb2..2413b31 100644 --- a/clients/gears.c +++ b/clients/gears.c @@ -23,6 +23,7 @@ #include "config.h" #include <stdint.h> +#include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> @@ -208,8 +209,13 @@ static void update_fps(struct gears *gears, uint32_t time) { long diff_ms; + static bool first_call = true; - gears->frames++; + if (first_call) { + gears->last_fps = time; + first_call = false; + } else + gears->frames++; diff_ms = time - gears->last_fps; @@ -437,8 +443,6 @@ gears_create(struct display *display) gears->view.rotx = 20.0; gears->view.roty = 30.0; - gettimeofday(&tv, NULL); - gears->last_fps = tv.tv_sec * 1000 + tv.tv_usec / 1000; printf("Warning: FPS count is limited by the wayland compositor or monitor refresh rate\n"); glEnable(GL_NORMALIZE); -- 2.0.4 _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel