On Thu 2022-04-28 15:10 -0300, Marcelo Tosatti wrote: > So you are syncing the vmstats on every system call return: Hi Marcelo, Sorry about the delay! No - indeed, that would be too expensive. If I understand correctly, Peter Zijlstra's feedback was in response to a previous suggestion made: "Could we *always* fold the vmstat counters when entering idle mode? ..." I think an exception should be made for the adaptive-tick mode/or a nohz_full CPU case when the scheduling-clock tick is stopped. Also, I feel correctness is key, as previously indicated since a significant divergence can impact memory reclaim code. > Have you measured performance of any system call heavy application > with this change? Unfortunately not. That being said, the aforementioned test and work will only take place under a nohz_full CPU and if the tick is stopped. So this should be somewhat limited, no? > Then the comment on why its so slow: > > "This loop is quite heavy. Maybe reducing the data necessary to be read > to a couple of cachelines would improve it considerably." > > The comment: > > "Is there anything that prevents a nohz full CPU from running an > application with short and frequent idling?" > > Is confusing and can be ignored. Understood. Kind regards, -- Aaron Tomlin
