dynamic memory allocation performance issues

[SteveDH]

Hi I'm trying to resolve some performance issues on the PSP with this. While looking at this I noticed it was doing loads of allocations and deletes.

Is there any way to reserve space at the start of a level and only have an allocation if I understimated.

I tried a couple of changes.

in
btCompoundCollisionAlgorithm::processCollision


I changed
manifoldArray.clear();
to
manifoldArray.resize(0);

which gave me a very small improvement

I then made manifoldArray a member variable gave me 6% increase in speed
and
changing some of the stacks in btDbvt (which is also used in btCompoundCollisionAlgorithm::processCollision) to
members gave me a further 14% increase in speed

so I managed to an overall get 20% increase in speed just by these 2 changes.

ok this is particular case, but allowing for pre allocation in some cases would also help with memory fragmentation.

I may also have missed an option somewhere so if it possible to get bullet to do this already could you please point me in the right direction.

thanks
Steve

[Erwin Coumans]

Thanks for the feedback. Do you have a patch for that (attach as zipfile here or in the google issue tracker)?

Thanks,
Erwin

[SteveDH]

sorry bit new to this, for a patch do I just zip up the source files or is it something more complicated

[pico]

Hi Steve,

in general i would suggest you implement an own allocator for Bullets allocations that should have its own heap. We use that in our games and it speeded up everything quite a bit. Bullet is already prepared to implement an own allocator.