SDL_Delay problem on laptop

SDL Development
1

Hi, All!

I’m writing my second SDL game and i have one strange problem with
SDL_Delay. I use SDL_Delay for generating delays between my frames
(every 5 msec). Everything works well on my Athlon 1200 and Duron 1000
workstations, but when i run my game on my laptop with Celeron 500, i see
that this delay began to work faster. I see that my sprites change each other
at least three times faster that i have on other computers.

What’s the problem? Can any guru help me?
Is SDL_Delay machine dependent?

My laptop config:

RedHat Linux 8.0, kernel 2.4.18-14
SDL version 1.2.4
Dell Lattitude CPx Celeron III 500Mhz, 128Mb

Thanks!–
Best regards,
Leo
Solvo Ltd.
St.Petersburg, Russia

2

Could this be because QueryPerformanceFrequency or the function use depends
on the clock speed of the processor and this speed is variable on your
labtop?> ----- Original Message -----

From: leo@solvo.ru (Leonid V. Khramov)
To: “SDL mailing list”
Sent: Thursday, April 03, 2003 4:38 PM
Subject: [SDL] SDL_Delay problem on laptop.

Hi, All!

I’m writing my second SDL game and i have one strange problem with
SDL_Delay. I use SDL_Delay for generating delays between my frames
(every 5 msec). Everything works well on my Athlon 1200 and Duron 1000
workstations, but when i run my game on my laptop with Celeron 500, i see
that this delay began to work faster. I see that my sprites change each
other
at least three times faster that i have on other computers.

What’s the problem? Can any guru help me?
Is SDL_Delay machine dependent?

My laptop config:

RedHat Linux 8.0, kernel 2.4.18-14
SDL version 1.2.4
Dell Lattitude CPx Celeron III 500Mhz, 128Mb

Thanks!

Best regards,
Leo
Solvo Ltd.
St.Petersburg, Russia

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

3

“Olaf van der Spek” writes:

Could this be because QueryPerformanceFrequency or the function use depends
on the clock speed of the processor and this speed is variable on your
labtop?

QueryPerformaceFrequency is a windows method and Leonid is running on
Linux.

That said, SDL_Delay on Linux probably isn’t what you want for 5 ms
delays. You can’t really hope to get better resolution than 15-20 ms
with it. Rather you might have to use (I know) busywaiting (using
sched_yield perhaps) or dynamic FPS scaling (i.e draw at full speed,
scaling movement to fit a certain FPS). Unfortunately there’s no
better options available unles you have root access (then you can use
/dev/rtc for perhaps down to 100-200 ?s sleep resolution).

Why it moves faster on the PDA I don’t know. Is there a difference in
the kernel between the laptop and the other boxes? Can you do a simple
test timing of SDL_Delay to see how long it REALLY sleeps?> ----- Original Message -----

From: “Leonid V. Khramov”
To: “SDL mailing list”
Sent: Thursday, April 03, 2003 4:38 PM
Subject: [SDL] SDL_Delay problem on laptop.

Hi, All!

I’m writing my second SDL game and i have one strange problem with
SDL_Delay. I use SDL_Delay for generating delays between my frames
(every 5 msec). Everything works well on my Athlon 1200 and Duron 1000
workstations, but when i run my game on my laptop with Celeron 500, i see
that this delay began to work faster. I see that my sprites change each
other
at least three times faster that i have on other computers.

What’s the problem? Can any guru help me?
Is SDL_Delay machine dependent?

My laptop config:

RedHat Linux 8.0, kernel 2.4.18-14
SDL version 1.2.4
Dell Lattitude CPx Celeron III 500Mhz, 128Mb

Thanks!

Best regards,
Leo
Solvo Ltd.
St.Petersburg, Russia

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

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