* Mathieu Desnoyers: > Adding the NUMA node id to struct rseq is a straightforward thing to do, > and a good way to figure out if anything in the user-space ecosystem > prevents extending struct rseq. > > This NUMA node id field allows memory allocators such as tcmalloc to > take advantage of fast access to the current NUMA node id to perform > NUMA-aware memory allocation. > > It is also useful for implementing NUMA-aware user-space mutexes. It can be used to implement getcpu purely in userspace, too. I had plan to hack this together with a node ID cache in TLS, which should offer pretty much the same functionality (except for weird CPU topology changes which alter the node ID of a previously used CPU). However, I do not understand the need for two fields here. Why isn't one enough? One field would also avoid the need to mess with rseq_cpu_id_state, maintaining API compatibility.
