On 8/13/25 15:43, Edgecombe, Rick P wrote: > I redid the test. Boot 10 TDs with 16GB of ram, run userspace to fault in memory > from 4 threads until OOM, then shutdown. TDs were split between two sockets. It > ended up with 1136 contentions of the global lock, 4ms waiting. 4ms out of how much CPU time? Also, contention is *NOT* necessarily bad here. Only _false_ contention. The whole point of the lock is to ensure that there aren't two different CPUs trying to do two different things to the same PAMT range at the same time. If there are, one of them *HAS* to wait. It can wait lots of different ways, but it has to wait. That wait will show up as spinlock contention. Even if the global lock went away, that 4ms of spinning might still be there.
