> Much of that is well addressed by one allocator arena per cpu, and either pinning threads to cpus or at least having a high threshold to move threads across N

> Much of that is well addressed by one allocator arena per cpu, and either pinning threads to cpus or at least having a high threshold to move threads across NUMA boundaries. Note that that can have an awkward effect: if the thread gets parked (either entirely, or just stops calling the allocator because it has reached its steady state), the allocator may never have the opportunity to release that thread's memory. IIRC mimalloc suffers from this issue, you need to call an allocator specific API to tell it about the regime change.