Messages in this thread | | | Subject | Re: [PATCH v2 3/5] mm/page_alloc: move pages to tail in move_to_free_list() | From | Vlastimil Babka <> | Date | Tue, 20 Oct 2020 19:20:22 +0200 |
| |
On 10/5/20 2:15 PM, David Hildenbrand wrote: > Whenever we move pages between freelists via move_to_free_list()/ > move_freepages_block(), we don't actually touch the pages: > 1. Page isolation doesn't actually touch the pages, it simply isolates > pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist. > When undoing isolation, we move the pages back to the target list. > 2. Page stealing (steal_suitable_fallback()) moves free pages directly > between lists without touching them. > 3. reserve_highatomic_pageblock()/unreserve_highatomic_pageblock() moves > free pages directly between freelists without touching them. > > We already place pages to the tail of the freelists when undoing isolation > via __putback_isolated_page(), let's do it in any case (e.g., if order <= > pageblock_order) and document the behavior. To simplify, let's move the > pages to the tail for all move_to_free_list()/move_freepages_block() users. > > In 2., the target list is empty, so there should be no change. In 3., > we might observe a change, however, highatomic is more concerned about > allocations succeeding than cache hotness - if we ever realize this > change degrades a workload, we can special-case this instance and add a > proper comment. > > This change results in all pages getting onlined via online_pages() to > be placed to the tail of the freelist. > > Reviewed-by: Oscar Salvador <osalvador@suse.de> > Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> > Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
| |