no-reply@allegro.cc (kovarex) — Mon, 15 Jun 2015 19:46:45 +0000

Related older topic: https://www.allegro.cc/forums/thread/615015

So I had this problem with performance, the game spent more and more time in the al_flip, and the time was also kind of random, but it could go up to 50ms.

After some investigation, I found out, the time is spent in the _al_d3d_prepare_bitmaps_for_reset that is called every flip, and goes through all of the (tens of thousands) sub-bitmaps we have just to find out it doesn't need to be updated.

More info in the version of the code we use now.

#SelectExpand
  1static void d3d_flip_display(ALLEGRO_DISPLAY *al_display)
  2{
  3   ALLEGRO_DISPLAY_D3D* d3d_display = (ALLEGRO_DISPLAY_D3D*)al_display;
  4   ALLEGRO_DISPLAY_WIN *win_display = &d3d_display->win_display;
  5   HRESULT hr;
  6
  7   if (d3d_display->device_lost)
  8      return;
  9
 10   al_lock_mutex(present_mutex);
 11
 12   d3d_display->device->EndScene();
 13
 14   hr = d3d_display->device->Present(NULL, NULL, win_display->window, NULL);
 15
 16   d3d_display->device->BeginScene();
 17
 18   al_unlock_mutex(present_mutex);
 19
 20   if (hr == D3DERR_DEVICELOST) {
 21      d3d_display->device_lost = true;
 22      return;
 23   }
 24   else {
 25      //_al_d3d_prepare_bitmaps_for_reset(d3d_display);
 26      
 27      // This (commenting out the method) is our custom solution of the performance problem of this method when
 28      // there are tens of thousands of sprites.
 29
 30      // In our case, vast majority of the sprites are either sub-bitmaps or bitmaps
 31      // marked with NO_PRESEVE flag, so the loop wastefully goes through all of the bitmaps
 32      // just to check, that none of these need to be updated.
 33
 34      // The proper solution would have to have special list of bitmaps that are relevant for the
 35      // reset (no subbitmaps, preserved), and check only those.
 36
 37   }
 38}

To avoid problems, I'm calling the _al_d3d_prepare_bitmaps_for_reset once all the game graphics is loaded, so the game bitmaps are preserved, but for the rest of the bitmaps, they are preserved manually.

The question is, is there something special I should be aware of?

no-reply@allegro.cc (SiegeLord) — Mon, 15 Jun 2015 20:33:54 +0000

Haha, wow, I'd never have thought that would become a performance bottleneck. Yes, what you're doing should be okay.

I should note that for the past 1 or 2 versions of 5.1, display->bitmaps no longer contains sub-bitmaps.

no-reply@allegro.cc (kovarex) — Mon, 15 Jun 2015 21:28:58 +0000

Thx for the info.

Severe performance problems with a lot of bitmaps and subbitmaps.