Buffer management and Stack size

[xliu0709]

Hi,
I was reading the code of software part and I saw there is a buffer management of weight buffer for convolution hardware functions. The function xiConstBufCreate() use the checkStack() function to check whether next allocated block of memory can fit in the STACK_SIZE with it's previous allocated block of memory. Other wise it shall allocate a new STACK_SIZE of memory. I tried to use normal sds_alloc without this specific memory buffer management for each buffer allocation and I do observed performance drop.
I want to know what is the reason of making this buffer management. How is the STACK_SIZE decided and why this pattern of memory allocation can have better performance than randomly assigned memory block by sds_alloc(). Thank you.