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This makes it > > > difficult to add new page_counters to a memcg and preserve the fast path > > > behavior. > > > > > > This series moves the stock into the page_counter layer. > > > page_counter_try_charge() consumes the stock, charges a batch to the > > > hierarchy on a miss, and refills the stock with the surplus. Memcg no > > > longer manages the stock in try_charge_memcg. > > > > > > So the stock keeps the existing layout, which is still a per-CPU bank > > > of 7 slots, each holding a count of precharged pages that it hands out. > > > It maintains exclusion using local locks on each CPU, and for remote > > > drains we schedule on the memcg workqueue. > > > > > > This change gives us the following benefits: > > > - Separate charge caching (page_counter) from charge policy (memcg). > > > - Makes it simple to keep stock out of interior cgroups on cgroup v2. > > > - Prepares for future work for stock improvement, which can now be > > > isolated from memcg changes. > > [...snip...] > > > Is the main motivation ease of addition of page_counters to a memcg? > > What would those counters be, why not add them here? > > Hi Balbir, > > Thank you for your interest in the series! So yes, that is the main > motivation but this series offers standalone benefits as well (which > are right above). > > The new page_counters that I want to add track per-tier per-memcg > residence. Those are used for enforcement (and not necessarily for > visibility), so I think they wouldn't make too much sense to add on > their own now, without the actual enforcement parts. > > What do you think? I've also linked my tiered memcg series [1] if you > wanted additional context. Thanks! I'll take a look. I was just curious based on the numbers I saw in the cover letter and wondering what the changes got, I can see how it helps in a hierarchial situation. > > Thank you, I hope you have a great day! > Joshua > > [1] https://lore.kernel.org/all/20260807202059.2620949-1-joshua.hahnjy@gmail.com/ Balbir