I forgot to right-shift the value so offsets were becoming 0 or 8
instead of 0-15. This fixes the management of small objects. It turns
out that after this fix, qfvis's problems were caused by fragmentation
in the windings. Need to revisit line allocation and use POT-specialized
pools.
They're binned by powers of two (with in between sizes going to the
smaller bin should I make cache-line allocations NPOT (which I think
might be worthwhile). However, there seems to still be a bug somewhere
causing a nasty leak as now my hacked qfvis consumes 40G in less than a
minute.
The idea is to not search through blocks for an available allocation.
While the goal was to speed up allocation of cache lines of varying
cluster sizes, it's not enough due to fragmentation.
This was inspired by
Hoard: A Scalable Memory Allocator
for Multithreaded Applications
Emery D. Berger, Kathryn S. McKinley, Robert D. Blumofe, Paul R.
Wilson,
It's not anywhere near the same implementation, but it did take a few
basic concepts. The idea is twofold:
1) A pool of memory from which blocks can be allocated and then freed
en-mass and is fairly efficient for small (4-16 byte) blocks
2) Tread safety for use with the Vulkan renderer (and any other
multi-threaded tasks).
However, based on the Hoard paper, small allocations are cache-line
aligned. On top of that, larger allocations are page aligned.
I suspect it would help qfvis somewhat if I ever get around to tweaking
qfvis to use cmem.
