On Fri 27-01-23 19:00:15, Minchan Kim wrote: [...] > Then, let me ask back to you. > > What statistcis in the current vmstat fields or pending fields > (to be merged) among accumulated counter stats sound reasonable > to be part of vmstat fields not tracepoint from your perspective? Most of those could be replaced but for historical reasons a counter was an only solution back then. Some metrics make a lot of sense these days as well. Regular snapshots of vmstat can give a nice overview of the _system_ reclaim activity. > Almost every stat would have corner cases by various reasons and > people would want to know the reason from process, context, function > or block scope depending on how they want to use the stat. > Even, tracepoint you're loving couldn't tell all the detail what they want > without adding more and more as on growing code chages. Quite possible but tracepoints are much easier to modify and shape to a particular need. > However, unlike your worry, people has used such an high level vague > vmstat fields very well to understand/monitor system health even though > it has various miscounting cases since they know the corner cases > are really minor. > > I am really curious what metric we could add in the vmstat instead of > tracepoint in future if we follow your logic. I would say that we should be more and more conservative when extending vmstat counters and use tracing instead as much as possible. I can imagine there could be cases where tracing is not a preferable option. Then we can judge case by case. So far you have presented no real argument, except you already collect vmstat on a larger scale and that would be easier (essentially free from the tool modification POV). That is a weak argument. Especially with a major design flaw already mentioned. I do not have much more to add here. -- Michal Hocko SUSE Labs
