SDL threads and gcc optimization

Hi!

My program (a raytracer) needs a lot of calculations so i thought it would be a good idear to use threads. I'm allready using the SDL lib in the program so the SDL threads seemed a good choice.
The program runs fine and a faster with treads, but it's still to slow. I tried speeding it up with the gcc optimization flags, but that just makes the program lock up. The optimization falgs works fine if i don't use threads.
I thought this might be a gcc thing so i tried compiling with visual studio, but with the exact same result: the program locks up right after it's started and i need to kill it, in order to close it.
During the lock up the program seems to run (~100% CPU usage).

- Has anyone tried to use the SDL threads alongside with compiler optimization?
- Can you recomend another way of using threads other than SDL, that would work better?

Thanks!
- JonLT

Apr 1 '08 #1

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2449

gpraghuram

1,275

Expert 1GB

I havent used SDL thread..
Why cant you try to use POSIX or ACE Framework thread for this?

Raghuram

Apr 2 '08 #2

JonLT

Thanks for your reply!

I just thought it would be easier to use the sdl threads. SDL is also crossplatform, which is importent, because we are developing as a group, and we use different OS's.

A small correction to the initial post. When the program locks up, it only uses one core.
This is the output from the gdb debugger:

Expand|Select|Wrap|Line Numbers

 
[Thread debugging using libthread_db enabled]

[New Thread -1215969088 (LWP 12883)]
 
... some output from the program before it reaches the main loop (not using threads)...
 
[New Thread -1314067568 (LWP 12886)]

[New Thread -1322460272 (LWP 12887)]

[New Thread -1330852976 (LWP 12888)]

[New Thread -1339245680 (LWP 12889)]

[New Thread -1347638384 (LWP 12890)]

[New Thread -1356031088 (LWP 12891)]

[Thread -1339245680 (LWP 12889) exited]

[Thread -1330852976 (LWP 12888) exited]

[Thread -1322460272 (LWP 12887) exited]

[Thread -1347638384 (LWP 12890) exited]

[Thread -1356031088 (LWP 12891) exited]

[Thread -1314067568 (LWP 12886) exited]

After this nothing happens, it just hangs.
This looks like the treads are only created the first time the main-loop is run, and not in every loop.
As i said in the initial post, this only happens when the optimization flag is turned on in the compiler.
Does anyone have an idea to what might be happening?

Apr 2 '08 #3

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