Up To 12.8x Improvement Observed For gup_test With New Linux MM Patches

Linux developer Rik van Riel has pulled off some nice Linux kernel optimizations over the years and the Meta engineer has been working on another one around batching of look-ups with Linux's follow_page_mask() that is used for translating virtual addresses to the corresponding struct page. With the Linux kernel's follow_page_mask() function currently walking the page tables one page at a time, Rik van Riel has been working on adapting it so walkers can hand back more than one page per call. This ability to batch look-ups in turn can provide for nice speed-ups for users of follow_page_mask() like Linux's get_user_pages() code. The Linux kernel's gup_test program for exercising get_user_pages() and other memory management exercises is showing some nice gains out of these request for comments (RFC) patches: Those interested in the Linux kernel memory management "MM" area or curious about this work can learn more via this patch series.