Re: [Qemu-devel] Re: Qemu 2D performance plunges below acceptable levels

[malc <av1474@comtv.ru>]

On Fri, 20 Feb 2009, Stefano Stabellini wrote:

> Paul Brook wrote:
> 
> >>      SDL_BlitSurface(guest_screen, &rec, real_screen, &rec);
> >> -    SDL_UpdateRect(real_screen, x, y, w, h);
> >> +    SDL_UpdateRects(real_screen, 1, &rec);
> > 
> > Have you actually tried this? I'd be amazed and dismayed if it made any 
> > difference. I can believe that SDL_UpdateRects is better that *multiple* 
> > calls to SDL_UpdateRect. However I see absolutely no justification for this 
> > change.
> > 
> 
> Of course I didn't: I don't have any MacOSX available and this is the
> main reason I am asking other people to test this patch and doing it myself.
> 
> >>From the documentation I thought they were implemented differently
> somehow but now that you make me think about it I went through the
> actual code and SDL_UpdateRect is implemented using SDL_UpdateRects :(
> 
> Also I don't how to explain the fact that SDL_Flip is faster than
> SDL_UpdateRect on MacOSX according to malc: the same libsdl macosx faq I
>  linked before claims that SDL_DOUBLEBUF is not even supported on MacOsX.

Let me reiterate - SDL_UpdateRect was REMOVED from sdl_update, SDL_Flip 
was added to _sdl_refresh_. So, no, SDL_Flip is NOT faster than
SDL_UpdateRect.

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