On 1/23/20 2:55 PM, Waiman Long wrote: > Playing with lock event counts, I would like you to change the meaning > intra_count parameter that you are tracking. Instead of tracking the > number of times a lock is passed to a waiter of the same node > consecutively, I would like you to track the number of times the head > waiter in the secondary queue has given up its chance to acquire the > lock because a later waiter has jumped the queue and acquire the lock > before it. This value determines the worst case latency that a secondary > queue waiter can experience. So Well, that is not strictly true as a a waiter in the middle of the secondary queue can go back and fro between the queues for a number of times. Of course, if we can ensure that when a FLUSH_SECONDARY_QUEUE is issued, those waiters that were in the secondary queue won't be put back into the secondary queue again. The parameter will then really determine the worst case latency. One way to do it is to store the tail of the secondary queue into the CNA node and passed it down the queue until it matches the current encoded tail. That will require changing both numa_node and intra_count into u16 to squeeze out space for another u32. That will also make the code a bit easier to analyze. Cheers, Longman
