It turns out that all the spikes were my fault. I'm deeply ashamed.. I
have failed to follow the most important rule of all, that says: profile
first! I was pretty sure my application was not the one causing the
stalls, since when I turned the other thread off, I got no spikes at all..
What happened is that I also called another small 3rd party library from
my main thread, but only when the other thread was also running. This
library converts coordinates between different projections (this is a
mapping software), and it seems like that sometimes it takes a pretty
long time to do this operation, that I assumed to be basically free. Now
I'm going to dive into this library, to see what's going on.
I think I've learned my lesson:
PROFILE, PROFILE, PROFILE! DO NOT MAKE ASSUMPTIONS! EVER!
Thanks,
Andras
Andras Balogh wrote:
> I'm developing a graphics application, that I want to be very
> responsive, very smooth, all the time! The rendering is pretty simple,
> the framerate is high and stable, so I just lock to vsync, and
> everything moves beautifully smooth! The CPU usage for this thread is
> always below 10%.
>
> However, I also have another thread, that has to do some heavy work.
> This thread does tons of IO operations, and also makes the CPU sweat!
>
> There is no synchronization between the two threads, so they should be
> able to run independently. Still, I'm experienceing sudden spikes in the
> framerate, when the second thread is really hammering. What could be the
> reason for this? Is it possible to do something about it, to regain the
> continuous framerate? I'm really not interested in the performance of
> the second thread, I just want my first thread to run as smooth as
> possible! I've tried lowering the priority for the second thread, and it
> does help, but there are still some spikes. Is it possible that it's
> Windows itself doing some operations at higher priority, like memory
> management, IO stuff, and the likes?
>
> Thanks,
>
>
> Andras
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