view test/torturethread.c @ 5053:b5b42be9333c

Fixed bug #1026 Vittorio Giovara 2010-07-16 19:09:28 PDT i was reading SDL_renderer_gles and i noticed that every time we there is some gl call the gl state is modified with a couple of glEnableClientState()/glDisableClientState. While this is completely fine for desktops systems, this is a major performace kill on mobile devices, right where opengles is implemented. Normal practice in this case is to update the glstate once, keep it always the same and disable/enable other states only in very special occasions. On the web there's plenty of documentation (on the top of my head http://developer.apple.com/iphone/library/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/Performance/Performance.html#//apple_ref/doc/uid/TP40008793-CH105-SW5 ) and i personally tried this. I modified my code and got a 10 fps boost, then modified SDL_render_gles and shifted from 40 fps to 50 fps alone -- considering that i started from ~30fps i got an 80% performance increase with this technique. I have attached a dif of my changes, hope that it will be included in mainstream.
author Sam Lantinga <slouken@libsdl.org>
date Wed, 19 Jan 2011 23:56:16 -0800
parents c121d94672cb
children
line wrap: on
line source


/* Simple test of the SDL threading code */

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>

#include "SDL.h"
#include "SDL_thread.h"

#define NUMTHREADS 10

static char volatile time_for_threads_to_die[NUMTHREADS];

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
    SDL_Quit();
    exit(rc);
}

int SDLCALL
SubThreadFunc(void *data)
{
    while (!*(int volatile *) data) {
        ;                       /*SDL_Delay(10); *//* do nothing */
    }
    return 0;
}

int SDLCALL
ThreadFunc(void *data)
{
    SDL_Thread *sub_threads[NUMTHREADS];
    int flags[NUMTHREADS];
    int i;
    int tid = (int) (uintptr_t) data;

    fprintf(stderr, "Creating Thread %d\n", tid);

    for (i = 0; i < NUMTHREADS; i++) {
        flags[i] = 0;
        sub_threads[i] = SDL_CreateThread(SubThreadFunc, &flags[i]);
    }

    printf("Thread '%d' waiting for signal\n", tid);
    while (time_for_threads_to_die[tid] != 1) {
        ;                       /* do nothing */
    }

    printf("Thread '%d' sending signals to subthreads\n", tid);
    for (i = 0; i < NUMTHREADS; i++) {
        flags[i] = 1;
        SDL_WaitThread(sub_threads[i], NULL);
    }

    printf("Thread '%d' exiting!\n", tid);

    return 0;
}

int
main(int argc, char *argv[])
{
    SDL_Thread *threads[NUMTHREADS];
    int i;

    /* Load the SDL library */
    if (SDL_Init(0) < 0) {
        fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
        return (1);
    }

    signal(SIGSEGV, SIG_DFL);
    for (i = 0; i < NUMTHREADS; i++) {
        time_for_threads_to_die[i] = 0;
        threads[i] = SDL_CreateThread(ThreadFunc, (void *) (uintptr_t) i);

        if (threads[i] == NULL) {
            fprintf(stderr, "Couldn't create thread: %s\n", SDL_GetError());
            quit(1);
        }
    }

    for (i = 0; i < NUMTHREADS; i++) {
        time_for_threads_to_die[i] = 1;
    }

    for (i = 0; i < NUMTHREADS; i++) {
        SDL_WaitThread(threads[i], NULL);
    }
    SDL_Quit();
    return (0);
}