[2.1] Multithreading cNumTransforms Topic is solved

[Rahzym]

Hello and sorry about my english. I'm working on the tutorial 06 multithreading sample. I don't understand what is cNumTransforms in GameEntityManager.cpp

Code: Select all

namespace Demo
{
    const size_t cNumTransforms = 250;

    GameEntityManager::GameEntityManager( Mq::MessageQueueSystem *graphicsSystem,
                                          LogicSystem *logicSystem ) :

Especially here :

Code: Select all

void GameEntityManager::aquireTransformSlot( size_t &outSlot, size_t &outBufferIdx )
{
    if( mAvailableTransforms.empty() )
    {
        GameEntityTransform *buffer = reinterpret_cast<GameEntityTransform*>( OGRE_MALLOC_SIMD(
                    sizeof(GameEntityTransform) * cNumTransforms * NUM_GAME_ENTITY_BUFFERS,
                    Ogre::MEMCATEGORY_SCENE_OBJECTS ) );
        mTransformBuffers.push_back( buffer );
        mAvailableTransforms.push_back( Region( 0, cNumTransforms, mTransformBuffers.size() - 1 ) );
    }

Is the value of cNumTransforms arbitrary ? or related to sizeof(GameEntityTransform) ?

[dark_sylinc]

Hi.

The value of cNumTransforms is arbitrary. The system works with pools of memory to reduce fragmentation and improve cache coherency, and each pool holds up to cNumTransforms entities. Large values of cNumTransforms will require more contiguous memory per pool (which makes the OS harder to fulfill because of virtual address space fragmentation, particularly relevant for 32 bit applications) small values of cNumTransforms will trash the cache more.