Pages
Hardware
- PAE, page tables, PTEs, TLB, MMU -- explain FIXME
Huge Pages
Making pages larger means fewer TLB misses for a given TLB size (due to more pages being supportable in the same amount of memory, due to narrower page identifiers), large mapping/releasing operations will be faster (due to fewer page table entries needing to be handled), and less memory is devoted to page table entries for a given amount of memory being indexed. The downside is possible wastage of main memory (due to pages not being used as completely). A 2002 paper from Navarro et al at Rice proposed transparent operating system support: "Transparent Operating System Support for Superpages". FreeBSD and Solaris ("[http://www.sun.com/blueprints/0304/817-5917.pdf support large pages transparently, while applications must explicitly take advantage of them on Linux (through at least 2.6.30).
Linux
- They were a 2003 Kernel Summit topic, after seeing first introduction in Linux 2.5.36 (LinuxGazette primer article)
- Rohit Seth provided the first explicit large page support to applications as covered in this LWN article
- alloc_hugepages, free_hugepages, get_large_pages(2) and shared_large_pages(2) were present in kernels 2.5.36-2.5.54
- hugetlbfs and assorted infrastructure replaced these. Mel Gorman's Linux MM wiki has a good page on hugetlbfs.
- Val Henson wrote a good 2006 KHB article in LWN on transparent largepage support
Applications
Page Clustering
Page clustering (implemented by William Lee Irwin for Linux in 2003, and not to be confused with page-granularity swap-out clustering). There's good coverage in this KernelTrap article. This is essentially huge pages without hardware support, and therefore with some overhead and no improvements in TLB-relative performance. It was written up in Irwin's 2003 OLS paper, "A 2.5 Page Clustering Implementation".