Re: [PATCH v1 1/1] mm: report per-page metadata information

David Hildenbrand
2023-09-14T13:01:18Z

On 13.09.23 19:30, 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.

It's probably worth mentioning, that in contrast to most other "memory
consumption" statistics, this metadata might not be included "MemTotal";
when the memmap is allocated using the memblock allocator, it's not
included, when it's dynamically allocated using the buddy (e.g., memory
hotplug), it's included.

--
Cheers,

David / dhildenb