On Fri 25-10-19 07:18:37, Qian Cai wrote: > > > > On Oct 25, 2019, at 3:26 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > Considering the pagetypeinfo is a debugging tool we do not really need > > exact numbers here. The primary reason to look at the outuput is to see > > how pageblocks are spread among different migratetypes and low number of > > pages is much more interesting therefore putting a bound on the number > > of pages on the free_list sounds like a reasonable tradeoff. > > > > The new output will simply tell > > [...] > > Node 6, zone Normal, type Movable >100000 >100000 >100000 >100000 41019 31560 23996 10054 3229 983 648 > > It was mentioned that developers could use this file is to see the > movement of those numbers for debugging, so this supposed to introduce > regressions as there is no movement anymore for those 100k+ items? Can you provide an explicit example please? As the changelog mentions it is the "low numbers" that is really interesting when debugging fragmentation issues. Because we are running out of a respective migrate type and it is interesting to see why and what compaction is doing etc. Having more than 100k pages on the respective migrate type list is a good sign that the migrate type is not in problems. Comparing multiple migrate types with >100k pages doesn't really need a large precision AFAIU. Now, I do agree that some debugging tools might get confused by > in the output but can we wait for reports and see whether anybody actually cares? It is more likely that fixing one off debugging tools wouldn't be a big deal. -- Michal Hocko SUSE Labs
