Isca 20 Session 6b Perforated Page Supporting Fragmented о Fig. 1. perforated pages support allocation of large pages even when the physical backing 2mb region is fragmented by immovable pages (center) and allows shared large pages to contain sub pages with different permissions (right). not shown: portions of perforated pages can be left unallocated to avoid physical memory bloat as well. The availability of large pages has dramatically improved the efficiency of address translation for applications that use large contiguous regions of memory. however, large pages can be difficult to allocate due to fragmented memory, non movable pages, or the need to split a large page into regular pages when part of the large page is forced to have a different permission status from the rest.
ççperforated çü ççpage çü õ õñºúíáõåàõ ÿõ µö µîüþóäþëçõîûþüäõåàõ ÿõêåúàì à Haslab Org •sparse access use in large pages àwasted physical space •rediswith large pages (4m keys, 16kb values) •20% morememory consumption(78gb à93gb) •45% fewertlb misses (1.8 mpki à1.1 mpki) 6 memory allocation actually used pages regular page large page large page. In this work, we enable the allocation of large 2mb pages even in the presence of fragmented physical memory via perforated pages. perforated pages permit the os to punch 4kb page sized holes in the physical address range allocated to a large page and re map them to other addresses as needed. Isca'20: the 47th international symposium on computer architecture session 6b: coherence, consistency, and memory title: perforated page: supporting fragment. Large pages deliver performance, but has challenges: contiguous, homogenous. compaction, bloating. immovable pages. perforated page provides flexible large page. large page translations for most of the data. holes to handle pages that differ. minimal changes to existing translation hw and data structure.
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