The Linux Virtual Memory System: Large Page Support

Intel x86 allows for the use of multiple page sizes, not just the standard 4-KB page. Specifically, recent designs support 2-MB and even 1-GB pages in hardware. Thus, over time, Linux has evolved to allow applications to utilize these huge pages (as they are called in the world of Linux).

Benefits of huge pages

Using huge pages, as hinted at earlier, leads to numerous benefits. As seen in VAX/VMS, doing so reduces the number of mappings that are needed in the page table; the larger the pages, the fewer the mappings. However, fewer page-table entries is not the driving force behind huge pages; rather, it’s better TLB behavior and related performance gains.

When a process actively uses a large amount of memory, it quickly fills up the TLB with translations. If those translations are for 4-KB pages, only a small amount of total memory can be accessed without inducing TLB misses. The result, for modern “big memory” workloads ...