[AD] Fw: Acquire/Release speed issue

["Eric Botcazou" <ebotcazou@xxxxxxxxxx>]

----- Original Message -----
From: "Robert Jr Ohannessian" <rohannessian@xxxxxxxxxx>
To: "Eric Botcazou" <ebotcazou@xxxxxxxxxx>
Sent: Tuesday, December 30, 2003 10:25 PM
Subject: Acquire/Release speed issue


>
> Hi,
>
> (Could you pls forward this to [AD]? Thanks)
>
> I have noticed something strange with the acquire/release speed of
> various bitmaps. Have a look at the attached test program.
>
> On my GeForce4 MX, I get the following result:
>
> Windowed mode:
> $ ./temp.exe
> screen: 1844 ticks
> video:  516 ticks
> sub-screen: 1844 ticks
> video2: 485 ticks
>
> Basically, create a video bitmap covering most of the screen, and
> locking that is way faster than locking the equivalent screen subbitmap.
>
> This leads me to believe there's a way to cut down on the
> acquire/release overhead by a factor of 3 somewhere in here (unless, of
> course, this is a bug).
>
>
> Full-screen mode:
> screen: 7157 ticks
> video:  4484 ticks
> sub-screen: 6859 ticks
> video2: 4735 ticks
>
> Here, FS is waaay slower than windowed mode(!). However, the same
> pattern can be seen: locking a video bitmap covering most of the screen
> is still faster than a sub-bitmap or the screen itself.
>
> Any ideas on what's going on?
>
>


----------------------------------------------------------------------------
----


> #include <time.h>
> #include "allegro.h"
>
> int main() {
>
> clock_t t0, t1, t2, t3, t4, t5;
> int i;
>
> allegro_init();
> set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0);
>
> BITMAP *bmp1 = create_video_bitmap(640, 480);
> BITMAP *bmp2 = create_video_bitmap(640, 479);
> BITMAP *bmp3 = create_sub_bitmap(bmp1, 0, 0, 640, 479);
>
> t0 = clock();
> for (i = 0; i < 1000000; i++) {
> acquire_bitmap(bmp1);
> release_bitmap(bmp1);
> }
> t1 = clock();
>
> for (i = 0; i < 1000000; i++) {
> acquire_bitmap(bmp2);
> release_bitmap(bmp2);
> }
> t2 = clock();
>
> for (i = 0; i < 1000000; i++) {
> acquire_bitmap(bmp3);
> release_bitmap(bmp3);
> }
> t3 = clock();
>
> destroy_bitmap(bmp3);
> destroy_bitmap(bmp2);
> destroy_bitmap(bmp1);
>
> set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
> set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0);
> bmp1 = create_video_bitmap(640, 479);
>
> t4 = clock();
> for (i = 0; i < 1000000; i++) {
> acquire_bitmap(bmp1);
> release_bitmap(bmp1);
> }
> t5 = clock();
>
> destroy_bitmap(bmp1);
> set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
> set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
>
> printf("screen: %i ticks\n", t1 - t0);
> printf("video:  %i ticks\n", t2 - t1);
> printf("sub-screen: %i ticks\n", t3 - t2);
> printf("video2: %i ticks\n", t5 - t4);
> return 0;
> }
> END_OF_MAIN()
>
>
--
Eric Botcazou

Attachment: temp.c
Description: Binary data