P4
FastTLABRefill is a platformdependent, macro assembly implemented, path for getting a new TLAB.
In C2 and in the interpreter there is a fast path for allocating objects in TLABs and a slow path in collectedheap.cpp for objects that doesn't fit, or for getting a new TLAB. The FastTLAB refill is a additional path were a new TLAB can be aquired without going into collectedheap. The benefit should be a slightly faster slow-path. The down side are more complex code, duplicate places for getting new TLABs making tracing harder or incomplete, pages of platform dependent code and icache bloat.
When running with G1 FastTLABRefill is disabled due to missing barriers.
We should investigate if FastTLABRefill still gives any performance improvement for two cases:
- c1 in general
- c1 in tiered
In C2 and in the interpreter there is a fast path for allocating objects in TLABs and a slow path in collectedheap.cpp for objects that doesn't fit, or for getting a new TLAB. The FastTLAB refill is a additional path were a new TLAB can be aquired without going into collectedheap. The benefit should be a slightly faster slow-path. The down side are more complex code, duplicate places for getting new TLABs making tracing harder or incomplete, pages of platform dependent code and icache bloat.
When running with G1 FastTLABRefill is disabled due to missing barriers.
We should investigate if FastTLABRefill still gives any performance improvement for two cases:
- c1 in general
- c1 in tiered