Memory allocations in btPoolAllocator

[screetch]

Hello,

I have been playing around with the new version of Bullet physics and hooked a debug allocator. I have seen that the btPoolAllocator allocated more than 40 megs of memory at startup (I haven't done anything with the world; barely created and destroyed the world).
Is there a reason for such a big pool ? it's for a pool of 65 000 btPersistentManifold, which are quite big.

On an x64 system, the size of the pool becomes 50 megs.

Moreover, it is possible to save 2 megs in this pool by reordering the fields of the btManifoldPoint structure and by putting the biggest fields first, so that there is no space lost due to alignment.
the current order is

Code: Select all

			btVector3 m_localPointA;			
			btVector3 m_localPointB;			
			btVector3	m_positionWorldOnB;
			///m_positionWorldOnA is redundant information, see getPositionWorldOnA(), but for clarity
			btVector3	m_positionWorldOnA;
			btVector3 m_normalWorldOnB;
		
			btScalar	m_distance1;
			btScalar	m_combinedFriction;
			btScalar	m_combinedRestitution;

         //BP mod, store contact triangles.
         int	   m_partId0;
         int      m_partId1;
         int      m_index0;
         int      m_index1;
				
			mutable void*	m_userPersistentData;
			btScalar		m_appliedImpulse;

			bool			m_lateralFrictionInitialized;
			btScalar		m_appliedImpulseLateral1;
			btScalar		m_appliedImpulseLateral2;
			int				m_lifeTime;//lifetime of the contactpoint in frames
			
			btVector3		m_lateralFrictionDir1;
			btVector3		m_lateralFrictionDir2;

by putting

Code: Select all

			btVector3 m_localPointA;			
			btVector3 m_localPointB;			
			btVector3	m_positionWorldOnB;
			///m_positionWorldOnA is redundant information, see getPositionWorldOnA(), but for clarity
			btVector3	m_positionWorldOnA;
			btVector3 m_normalWorldOnB;
			btVector3		m_lateralFrictionDir1;
			btVector3		m_lateralFrictionDir2;
		
			mutable void*	m_userPersistentData;

			btScalar	m_distance1;
			btScalar	m_combinedFriction;
			btScalar	m_combinedRestitution;

			btScalar		m_appliedImpulse;
			btScalar		m_appliedImpulseLateral1;
			btScalar		m_appliedImpulseLateral2;

			int				m_lifeTime;//lifetime of the contactpoint in frames

         //BP mod, store contact triangles.
         int	   m_partId0;
         int      m_partId1;
         int      m_index0;
         int      m_index1;
				

			bool			m_lateralFrictionInitialized;

the size of the struc goes down from 176 to 168 (64bits only). for 65536*4*8 bytes (2 megs)
On the bright side, thanks for the clean clean-up; a world leaves no memory when you destroy it. I am of the few people that want a program to have released everything at shut down and it's great to see no memory leak =) (which shows you are keeping good track of the usage of memory).

/n