On Mon 26-10-15 12:56:19, Johannes Weiner wrote: [...] > Now you could argue that there might exist specialized workloads that > need to account anonymous pages and page cache, but not socket memory > buffers. Exactly, and there are loads doing this. Memcg groups are also created to limit anon/page cache consumers to not affect the others running on the system (basically in the root memcg context from memcg POV) which don't care about tracking and they definitely do not want to pay for an additional overhead. We should definitely be able to offer a global disable knob for them. The same applies to kmem accounting in general. I do understand with having the accounting enabled by default after we are reasonably sure that both kmem/tcp are stable enough (which I am not convinced about yet to be honest) but there will be always special loads which simply do not care about kmem/tcp accounting and rather pay a global balancing price (even OOM) rather than a permanent price. And they should get a way to opt-out. > Or any other combination of pick-and-choose consumers. But > honestly, nowadays all our paths are lockless, and the counting is an > atomic-add-return with a per-cpu batch cache. You are still hooking into hot paths and there are users who want to squeeze every single cycle from the HW. > I don't think there is a compelling case for an elaborate interface > to make individual memory consumers configurable inside the memory > controller. I do not think we need an elaborate interface. We just want to have a global boot time knob to overwrite the default behavior. This is few lines of code and it should give the sufficient flexibility. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>