Identification of low-activity large memory pages

摘要

Large pages that may impede memory performance in computer systems are identified. In operation, mappings to selected large pages are temporarily demoted to mappings to small pages and accesses to these small pages are then tracked. For each selected large page, an activity level is determined based on the tracked accesses to the small pages included in the large page. By strategically selecting relatively low activity large pages for decomposition into small pages and subsequent memory reclamation while restoring the mappings to relatively high activity large pages, memory consumption is improved, while limiting performance impact attributable to using small pages.

主权项

1. A method of classifying an activity level for large pages in a computer system having memory that is partitioned and accessed as small pages and large pages, comprising:
selecting a plurality of large pages; for each of the large pages in the plurality of large pages, identifying each small page included in the large page and clearing an accessed bit for the small page to enable tracking of accesses to the small page from the time the small page accessed bit is cleared; scanning the accessed bits for the small pages that are included in the large page after a first scan period; and for each of the large pages in the plurality of large pages, determining a first activity level of the large page based on the accessed bits for the small pages that are included in the large page, each of the accessed bits for a small page indicating whether or not the small page has been accessed during the first scan period.