> > Since we are going to use two independent interfaces > > /proc/meminfo/PageMetadata and nodeN/page_metadata (in a separate file > > as requested by Greg) How about if in /proc/meminfo we provide only > > the buddy allocator part, and in nodeN/page_metadata we provide the > > total per-page overhead in the given node that include memblock > > reserves, and buddy allocator memory? > > What we want is the system-wide breakdown of kernel memory usage. It > works for this use case with the new PageMetadata counter in > /proc/meminfo to report only buddy-allocated per-page metadata. We want to report all PageMetadata, otherwise this effort is going to be useless for the majority of users. As you noted, /proc/meminfo allows us to report only the part of per-page metadata that was allocated by the buddy allocator because of an existing MemTotal bug that does not include memblock reserves. However, we do not have this limitation when we create a new nodeN/page_metadata interface, and we can document that in the sysfs ABI documentation: sum(nodeN/page_metadata) contains all per-page metadata and is superset of /proc/meminfo. The only question is how to name PageMetadata in the /proc/meminfo appropriately, so users can understand that not all page metadata is included? (of course we will also document that only the MemTotal part of page metadata is reported in /proc/meminfo) Pasha
