On Tue, Oct 17, 2023 at 05:55:48PM -0700, Sourav Panda wrote: > Adds a new per-node PageMetadata field to > /sys/devices/system/node/nodeN/meminfo > and a global PageMetadata field to /proc/meminfo. This information can > be used by users to see how much memory is being used by per-page > metadata, which can vary depending on build configuration, machine > architecture, and system use. > > Per-page metadata is the amount of memory that Linux needs in order to > manage memory at the page granularity. The majority of such memory is > used by "struct page" and "page_ext" data structures. In contrast to > most other memory consumption statistics, per-page metadata might not > be included in MemTotal. For example, MemTotal does not include memblock > allocations but includes buddy allocations. While on the other hand, > per-page metadata would include both memblock and buddy allocations. > > This memory depends on build configurations, machine architectures, and > the way system is used: > > Build configuration may include extra fields into "struct page", > and enable / disable "page_ext" > Machine architecture defines base page sizes. For example 4K x86, > 8K SPARC, 64K ARM64 (optionally), etc. The per-page metadata > overhead is smaller on machines with larger page sizes. > System use can change per-page overhead by using vmemmap > optimizations with hugetlb pages, and emulated pmem devdax pages. > Also, boot parameters can determine whether page_ext is needed > to be allocated. This memory can be part of MemTotal or be outside > MemTotal depending on whether the memory was hot-plugged, booted with, > or hugetlb memory was returned back to the system. > > Suggested-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx> > Signed-off-by: Sourav Panda <souravpanda@xxxxxxxxxx> > Change-Id: I4351791c9f4c1e9759cbd8e646e808565dbb595f checkpatch.pl should have said that "Change-Id:" should be removed, why didn't you run this on your patch before submitting it? thanks, greg k-h
