On Tue 13-01-26 08:51:45, Mathieu Desnoyers wrote: > On 2026-01-13 04:24, Michal Hocko wrote: [...] > - Introduce new proc files, e.g. > > /proc/<pid>/rss/approximate > /proc/<pid>/rss/precise > > Where the "approximate" file would export the following lines for each > page type (MM_FILEPAGES, MM_ANONPAGES, MM_SWAPENTS, MM_SHMPAGES, > allowing future additions): > > <page type> <approximate> <precise_sum_min> <precise_sum_max> > > And "precise" would export lines for each page type: > > <page type> <precise_sum> > > The key thing here is to have different files to query approximated > vs precise values, so we don't have the overhead of the precise sum > when all we need is an approximation. > > This would expose all the bits and pieces needed to allow userspace to > implement something similar to the 2-pass algorithm I'm proposing for > the OOM killer, but tweaked for other use-cases. > > This proposed ABI is purely hypothetical at this stage. Please let me > know if you have something different in mind.
TBH, I am not convinced this is really needed. I would simply use the new more-precise interface for /proc/<pid>/stat with numbers of potential overhead payed by an increased precision. If we need to revert to low precision then we can do that based on a specific report. > When you mention "highlevel doc", which document do you have in mind ? > Something related to lib/percpu_counter_tree.c or to the /proc ABI ? Documentation/core-api/percpu_counter_tree.rst -- Michal Hocko SUSE Labs
