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| High CPU usage when flipping backbuffers on OpenGL display |
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titonbrujah
Member #11,156
July 2009
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Hey guys... I noticed some weird CPU usage while developing a project using an opengl window in allegro 5.0.5 Basically, the program was using ~15% cpu time (a core on some 60% usage since both machines I tested were quad-cores) I removed all calls to the rest of my program and compiled this source code: 1#include <iostream>
2#include <allegro5/allegro.h>
3#include <memory>
4//#include "Game.h"
5#include <allegro5/allegro_primitives.h>
6#include <allegro5/allegro_font.h>
7#include <allegro5/allegro_ttf.h>
8#include <allegro5/allegro_image.h>
9
10const int FPS = 60;
11
12bool initializeAllegro(ALLEGRO_DISPLAY*& display, ALLEGRO_EVENT_QUEUE*& queue, ALLEGRO_TIMER*& timer) {
13 if (!al_init()) return false;
14 if(!al_init_image_addon()) {
15 std::cout << "Error initializing image addon!\n";
16 return false;
17 }
18 if (!al_install_keyboard()){
19 std::cout << "Error installing keyboard!\n";
20 return false;
21 }
22 if (!al_install_mouse()){
23 std::cout << "Error installing mouse!\n";
24 return false;
25 }
26 al_set_new_display_flags(ALLEGRO_OPENGL);
27 //display = al_create_display(Game::WIDTH, Game::HEIGHT);
28 display = al_create_display(800, 800);
29 if (!display){
30 std::cout << "Error creating display!\n";
31 return false;
32 }
33 al_init_font_addon();
34 if (!al_init_ttf_addon()){
35 std::cout << "Error initializing TTF!\n";
36 return false;
37 }
38 if (!al_init_primitives_addon()){
39 std::cout << "Error initializing primitives!\n";
40 return false;
41 }
42 queue = al_create_event_queue();
43 if (!queue){
44 std::cout << "Error creating queue!\n";
45 return false;
46 }
47 al_register_event_source(queue, al_get_display_event_source(display));
48 al_register_event_source(queue, al_get_keyboard_event_source());
49// if (al_hide_mouse_cursor(display) && al_grab_mouse(display)) {
50// al_register_event_source(queue, al_get_mouse_event_source());
51// } else al_show_mouse_cursor(display);
52 timer = al_create_timer(1.0/FPS);
53 if (!timer) {
54 std::cout << "Error creating timer!\n";
55 return false;
56 }
57 al_start_timer(timer);
58 al_register_event_source(queue, al_get_timer_event_source(timer));
59 {
60 ALLEGRO_PATH* p = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
61 al_set_path_filename(p, "");
62 al_append_path_component(p, "data");
63 al_make_path_canonical(p);
64// std::cout << al_path_cstr(p, '/');
65 al_change_directory(al_path_cstr(p, '/'));
66 al_destroy_path(p);
67 }
68 return true;
69}
70
71int main(){
72 ALLEGRO_DISPLAY* display = nullptr;
73 ALLEGRO_EVENT_QUEUE* queue = nullptr;
74 ALLEGRO_TIMER* timer = nullptr;
75 if (!initializeAllegro(display, queue, timer)){
76 std::cout << "Error during allegro initialization!\n";
77 al_rest(10);
78 return 1;
79 }
80// auto game = std::make_shared<Game>();
81 bool cont = true;
82 bool redraw = true;
83 while (cont
84 //&& !game->isOver()
85 ){
86 ALLEGRO_EVENT ev;
87 al_wait_for_event(queue, &ev);
88 const ALLEGRO_EVENT_TYPE type = ev.type;
89 switch(type){
90 case ALLEGRO_EVENT_DISPLAY_CLOSE:
91 cont = false;
92 break;
93 case ALLEGRO_EVENT_TIMER:
94 //game->step();
95 redraw = true;
96 break;
97 case ALLEGRO_EVENT_MOUSE_AXES:
98// al_set_mouse_xy(display, Game::WIDTH/2.0f, Game::HEIGHT/2.0f);
99 default:
100 //game->onEvent(ev);
101 break;
102 }
103 if (redraw && al_event_queue_is_empty(queue)){
104 redraw = false;
105 //game->draw();
106 al_flip_display();
107 }
108 }
109
110 al_destroy_event_queue(queue);
111 al_destroy_timer(timer);
112 al_uninstall_keyboard();
113 al_uninstall_mouse();
114 al_destroy_display(display);
115 return 0;
116}
windows binary: http://www.allegro.cc/files/attachment/605652 Still uses ~15% cpu on both machines I tested (both quad-cores, one with a GeForce 9800 GTX and one with a 430). Tried updating the graphics drivers on the 430 and running the program for about 20 minutes, but nothing changed. Either commenting out al_flip_display(); (line 106) or al_set_new_display_flags(ALLEGRO_OPENGL); (line 26) made cpu usage plummet down to 0% <My Allegro projects> |
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jmasterx
Member #11,410
October 2009
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I have always had this problem on my laptop for some reason. Have you tried toggling vsync on / off? That's what solved it on my laptop. Well, I still do not get nearly as low a cpu usage as with D3D, but it helped. Agui GUI API -> https://github.com/jmasterx/Agui |
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titonbrujah
Member #11,156
July 2009
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jmasterx said: I have always had this problem on my laptop for some reason. Have you tried toggling vsync on / off? That's what solved it on my laptop. Well, I still do not get nearly as low a cpu usage as with D3D, but it helped.
Indeed, adding al_set_new_display_option(ALLEGRO_VSYNC, 2, ALLEGRO_REQUIRE) (force vsync off) right before creating the display made cpu usage oscillate between 0% and 1% Still, I think this is something worth looking into... It's probably just some code not yielding the cpu while waiting for the vsync, but the game was running a bit choppy before this and it's much better now <My Allegro projects> |
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Thomas Fjellstrom
Member #476
June 2000
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Allegro itself doesn't wait for vsync. It lets the video driver (or hardware) do it. So if there's a problem, its not something we can really fix. -- |
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Max Savenkov
Member #4,613
May 2004
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I had that problem a while ago with GeForce 560 Ti on Windows 7. Had to disable VSync by default and implement frame-limit. No tearing (that I can see), and performance is great.
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