On Fri, May 6, 2022 at 7:57 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > On Thu, May 05, 2022 at 05:13:30AM -0700, Ganesan Rajagopal wrote: > > v1 memcg exports memcg->watermark as "memory.mem_usage_in_bytes" in > > sysfs. This is missing for v2 memcg though "memory.current" is exported. > > There is no other easy way of getting this information in Linux. > > getrsuage() returns ru_maxrss but that's the max RSS of a single process > > instead of the aggregated max RSS of all the processes. Hence, expose > > memcg->watermark as "memory.watermark" for v2 memcg. > > > > Signed-off-by: Ganesan Rajagopal <rganesan@xxxxxxxxxx> > > This wasn't initially added to cgroup2 because its usefulness is very > specific: it's (mostly) useless on limited cgroups, on long-running > cgroups, and on cgroups that are recycled for multiple jobs. And I > expect these categories apply to the majority of cgroup usecases. > > However, for the situation where you want to measure the footprint of > a short-lived, unlimited one-off cgroup, there really is no good > alternative. And it's a legitimate usecase. It doesn't cost much to > maintain this info. So I think we should go ahead with this patch. > > But please add a blurb to Documentation/admin-guide/cgroup-v2.rst. No objection from me. I do have two points: (1) watermark is not a good name for this interface, maybe max_usage or something. (2) a way to reset (i.e. write to it, reset it).
