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.
