Dave Chinner <david@xxxxxxxxxxxxx> writes: > Thoughts, comments, etc? The interesting part is if it will cause additional tail latencies allocating under fragmentation with direct reclaim, compaction etc. being triggered before it falls back to the base page path. In fact it is highly likely it will, the question is just how bad it is. Unfortunately benchmarking for that isn't that easy, it needs artificial memory fragmentation and then some high stress workload, and then instrumenting the transactions for individual latencies. I would in any case add a tunable for it in case people run into this. Tail latencies are a common concern on many IO workloads. -Andi
