On 09/15/2017 04:49 AM, Michal Hocko wrote: > Why do we need an auto-mode? Is it safe to enforce by default.
Do we *need* it? Not really. But, it does offer the best of both worlds: The vast majority of users see virtually no impact from the counters. The minority that do need them pay the cost *and* don't have to change their tooling at all. > Is it> possible that userspace can get confused to see 0 NUMA stats in the > first read while other allocation stats are non-zero? I doubt it. Those counters are pretty worthless by themselves. I have tooling that goes and reads them, but it aways displays deltas. Read stats, sleep one second, read again, print the difference. The only scenario I can see mattering is someone who is seeing a performance issue due to NUMA allocation misses (or whatever) and wants to go look *back* in the past. A single-time printk could also go a long way to keeping folks from getting confused.
