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[[File:X86 64.png|x86_64 page table layout|thumb|right]]

Every memory access on a virtual memory requires translation. These translations are typically cached in a Translation Lookaside Buffer (TLB). A TLB miss requires an expensive page table walk, requiring several memory accesses of its own. Larger pages mean more address space translated by each TLB and page table entry, and can thus lead to higher performance.

Linux does not allow deterministic use of huge pages without special privileges, so as not to allow denials of service. Using <tt>madvise(2)</tt> with <tt>MADV_HUGEPAGE</tt> (available since 2.6.38) indicates that the specified memory is suitable for transparent huge pages, but provides no feedback and guarantees nothing. The much newer (6.1) <tt>MADV_COLLAPSE</tt> performs a synchronous best-effort movement into transparent huge pages, and seems refreshingly general and robust. <tt>mmap(2)</tt> can specify <tt>MMAP_HUGETLB</tt> since 2.6.32, but pages must have already been made available by the administrator (the mapping still requires <tt>CAP_IPC_LOCK</tt>). Pages are made available via the [[sysfs]] interface, the kernel command line, or via mounting the hugetlbfs filesystem. This last provides named hugetlb-backed maps. <tt>shmget(2)</tt> since 2.6 has supported <tt>SHM_HUGETLB</tt> for shared memory segments.

==Hardware==

* PAE, PSE, PSE36, page tables, PTEs, TLB, MMU, PGD -- explain ''FIXME''

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 [[File:X86 64.png|x86_64 page table layout|thumb|right]]
+Every memory access on a virtual memory requires translation. These translations are typically cached in a Translation Lookaside Buffer (TLB). A TLB miss requires an expensive page table walk, requiring several memory accesses of its own. Larger pages mean more address space translated by each TLB and page table entry, and can thus lead to higher performance.
+Linux does not allow deterministic use of huge pages without special privileges, so as not to allow denials of service. Using <tt>madvise(2)</tt> with <tt>MADV_HUGEPAGE</tt> (available since 2.6.38) indicates that the specified memory is suitable for transparent huge pages, but provides no feedback and guarantees nothing. The much newer (6.1) <tt>MADV_COLLAPSE</tt> performs a synchronous best-effort movement into transparent huge pages, and seems refreshingly general and robust. <tt>mmap(2)</tt> can specify <tt>MMAP_HUGETLB</tt> since 2.6.32, but pages must have already been made available by the administrator (the mapping still requires <tt>CAP_IPC_LOCK</tt>). Pages are made available via the [[sysfs]] interface, the kernel command line, or via mounting the hugetlbfs filesystem. This last provides named hugetlb-backed maps. <tt>shmget(2)</tt> since 2.6 has supported <tt>SHM_HUGETLB</tt> for shared memory segments.
 ==Hardware==
 * PAE, PSE, PSE36, page tables, PTEs, TLB, MMU, PGD -- explain ''FIXME''