On Wed, 2022-06-15 at 13:11 +0200, Michal Hocko wrote: > On Tue 14-06-22 15:25:32, Tim Chen wrote: > > For controlling usage of a top tiered memory by a cgroup, accounting > > of top tier memory usage is needed. This patch set implements the > > following: > > > > Patch 1 introduces interface and simple implementation to retrieve > > cgroup tiered memory usage > > Patch 2 introduces more efficient accounting with top tier memory page counter > > Patch 3 provides a sysfs interface to repot the the top tiered memory > > usage. > > I guess you meant cgroupfs here, right? Yes. > > > The patchset works with Aneesh's v6 memory-tiering implementation [1]. > > It is a preparatory patch set before introducing features to > > control top tiered memory in cgroups. > > > > I'll like to first get feedback to see if > > (1) Controllng the topmost tiered memory is enough > > or > > (2) Multiple tiers at the top levels need to be grouped into "toptier" > > or > > (3) There are use cases not covered by (1) and (2). > > I would start by asking why do we need a dedicated interface in the > first place. Why the existing numa_stat is not a proper interface. Right > now we only report LRU per node stats. Is this insufficient? > What is userspace expect to do based on the reported data? Exporting the toptier information here is convenient for me for debugging purpose of seeing whether a cgroup's toptier usage is under control. Otherwise writing a script to parse numastat and the memtier heirachy will work too. Exporting toptier usage directly is optional and we don't have to do it. Tim
