[SDL] CPU usage

[Edward Byard]

I think I've sorted it.

I used to have a while (SDL_PollEvent) which is now an if (SDL_PollEvent) which handles the input,
and then put a 50ms delay outside this which brings the CPU down to 30%.

A bit more code re-organising and using a delay in some major animation work has got CPU usage down to
30% and made the system more stable and, it seems, the animation is much smoother.

Thanks for your advice!

Ed

----- Original Message ----
From: Alvin <alvinbeach at gmail.com>
To: sdl at lists.libsdl.org
Sent: Friday, 8 February, 2008 5:55:24 PM
Subject: Re: [SDL] CPU usage

On 
Friday 
08 
February 
2008 
13:43:02 
Edward 
Byard 
wrote:
> 
Hi
>
> 
My 
SDL 
app 
hogs 
the 
CPU 
unless 
in 
a 
state 
where 
I'm 
waiting 
for 
user 
input.
> 
Since 
I'm 
using 
SDL_PollEvent, 
I 
never 
miss 
an 
event, 
but 
CPU 
is 
at 
100%
> 
the 
whole 
time.
>
> 
If 
I 
put 
a 
100ms 
delay 
every 
pass 
of 
the 
loop, 
CPU 
drops 
to 
~25% 
which 
is
> 
fine.
>
> 
So....how 
do 
I 
get 
CPU 
usage 
down 
to 
the 
~25% 
figure 
without 
using 
a 
delay
> 
in 
the 
loop?
>
> 
This 
isn't 
a 
Windows 
app, 
just 
a 
console 
app.
>
> 
Any 
help 
muchly 
appreciated!
>
> 
Ed

It's 
hard 
to 
say 
without 
knowing 
how 
you 
are 
using 
SDL_PollEvent. 
If 
I 
had 
to 
guess, 
I 
say 
you 
are 
doing 
a 
spin-loop 
on 
it. 
In 
case 
you 
missed 
it, 
SDL_PollEvent 
returns 
right 
away 
regardless 
if 
events 
are 
in 
the 
queue. 
If 
you 
are 
constantly 
calling 
SDL_PollEvent, 
then 
I'd 
fully 
expect 
it 
to 
behave 
as 
you 
said.

Have 
a 
look 
at 
SDL_WaitEvent() 
and 
see 
if 
it 
fits 
into 
your 
program. 
If 
you 
aren't 
sure, 
can 
you 
post 
an 
example 
of 
how 
you 
read/poll 
the 
events?

Alvin
_______________________________________________
SDL 
mailing 
list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org






      ___________________________________________________________
Yahoo! Answers - Got a question? Someone out there knows the answer. Try it
now.
http://uk.answers.yahoo.com/ 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.libsdl.org/pipermail/sdl-libsdl.org/attachments/20080208/9d12fdec/attachment.htm