On 2/24/22 15:41, Muchun Song wrote: > On Thu, Feb 24, 2022 at 3:48 AM Joao Martins <joao.m.martins@xxxxxxxxxx> wrote: >> >> Currently memmap_init_zone_device() ends up initializing 32768 pages >> when it only needs to initialize 128 given tail page reuse. That >> number is worse with 1GB compound pages, 262144 instead of 128. Update >> memmap_init_zone_device() to skip redundant initialization, detailed >> below. >> >> When a pgmap @vmemmap_shift is set, all pages are mapped at a given >> huge page alignment and use compound pages to describe them as opposed >> to a struct per 4K. >> >> With @vmemmap_shift > 0 and when struct pages are stored in ram >> (!altmap) most tail pages are reused. Consequently, the amount of >> unique struct pages is a lot smaller that the total amount of struct > > s/that/than/g Fixed as well.
