On Fri, 9 Aug 2024 21:21:15 +0000 kaiyang2@xxxxxxxxxx wrote: > From: Kaiyang Zhao <kaiyang2@xxxxxxxxxx> > > The ability to observe the demotion and promotion decisions made by the > kernel on a per-cgroup basis is important for monitoring and tuning > containerized workloads on either NUMA machines or machines > equipped with tiered memory. > > Different containers in the system may experience drastically different > memory tiering actions that cannot be distinguished from the global > counters alone. > > For example, a container running a workload that has a much hotter > memory accesses will likely see more promotions and fewer demotions, > potentially depriving a colocated container of top tier memory to such > an extent that its performance degrades unacceptably. > > For another example, some containers may exhibit longer periods between > data reuse, causing much more numa_hint_faults than numa_pages_migrated. > In this case, tuning hot_threshold_ms may be appropriate, but the signal > can easily be lost if only global counters are available. > > This patch set adds five counters to > memory.stat in a cgroup: numa_pages_migrated, numa_pte_updates, > numa_hint_faults, pgdemote_kswapd and pgdemote_direct. > > count_memcg_events_mm() is added to count multiple event occurrences at > once, and get_mem_cgroup_from_folio() is added because we need to get a > reference to the memcg of a folio before it's migrated to track > numa_pages_migrated. The accounting of PGDEMOTE_* is moved to > shrink_inactive_list() before being changed to per-cgroup. > Thanks. I lack the operational experience to be able to judge the usefulness of this - hopefully others can weigh in. Meanwhile, the patch is simple enough - I'll queue it up for testing.
