60 FPS limit in linux?

Frank Drebin

I noticed that when running any Allegro 5 program in linux, I can't get more than 60 FPS - even though al_clear_to_color(al_map_rgb(0,0,0)) only is called and nothing is drawn. How does that come?

BTW: I am using the Allegro 5 version that can be found in the Ubuntu PPAs

Eric Johnson

1. Are you using a timer? If so, what is it set to?

2. How are you measuring FPS?

3. Is v-sync enabled?

4. Can you post the code?

Frank Drebin

3. I don't know. At least I didn't enable it myself...
1., 2., and 4.:

#SelectExpand
  1#include <stdio.h>
  2#include <allegro5/allegro.h>
  3
  4#define duration 5
  5
  6int frames=0;
  7bool quit=0;
  8
  9int main(int argc,char** argv)
 10{
 11    if (!al_init()) return -1;
 12
 13    ALLEGRO_DISPLAY* display=al_create_display(640,480);
 14    if (!display) return -1;
 15
 16    ALLEGRO_EVENT event;
 17    ALLEGRO_EVENT_QUEUE* queue=al_create_event_queue();
 18    ALLEGRO_TIMER* timer=al_create_timer(duration);
 19    al_start_timer(timer);
 20    al_register_event_source(queue,al_get_timer_event_source(timer));
 21
 22    while (!quit)
 23    {
 24       if (al_wait_for_event_timed(queue,&event,0)) quit=1;
 25
 26       if (al_is_event_queue_empty(queue))
 27       {
 28          al_clear_to_color(al_map_rgb(0,0,0));
 29          al_flip_display();
 30          frames++;
 31       }
 32    }
 33
 34    printf("FPS: %i\n",frames/duration);
 35
 36    al_destroy_display(display);
 37    al_destroy_event_queue(queue);
 38    al_destroy_timer(timer);
 39
 40    return 0;
 41}

Edgar Reynaldo

The Fine Manual entry on al_set_new_display_option said:

ALLEGRO_VSYNC
Set to 1 to tell the driver to wait for vsync in al_flip_display, or to 2 to force vsync off. The default of 0 means that Allegro does not try to modify the vsync behavior so it may be on or off. Note that even in the case of 1 or 2 it is possible to override the vsync behavior in the graphics driver so you should not rely on it.

Frank Drebin

Thanks - didn't know that vsync was enabled...

Chris Katko

You can also configure VSYNC on the driver level.

There's at least two ways, google it. I've posted before in these forums but I don't recall the command line arguments. nVidia has one set. And there's one universal set too. It's like VSYNC=1/2/3/4. With 4 maybe being adaptive vsync.

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