Mike Lambert wrote: > At one point, we had a mem_alloc_aligned, which guaranteed the start of a > block of memory given any pointer into the contents of the block. If we > store a pointer to the pool at the beginning of each set of headers, then > we navoid the need for a per-header pool pointer, at the cost of a bit > more math and an additional dereference to get at it. > > - it imposes additional memory requirements in order to align the block of > memory, and imposes a bit more in this 'header header' at the beginning of > the block of headers. I considered this option also, but dismissed it as you need to allocate twice the required size to get guaranteed alignment, so you are better off with the pointer per header. To use this method without the memory overhead would require implementing another allocator: if you want for example a 1K aligned block, first allocate 16K, discard the amount before the alignment point, and dish out the rest as 15 (or 16 if you're really lucky) 1K aligned pages. I seriously considered this when I changed my buffer memory to be paged instead of a single allocation per memory pool; but I haven't actually implemented it yet.
-- Peter Gibbs EmKel Systems
