I've never understood Linus' aversion against general support for superpages. He always seems to make use of this argument that it does not matter (performance or otherwise). However, at the OSDI '02 Navarro published a very thorough analysis of how superpage support helped performance by increasing TLB coverage . The page sizes used were 8KB, 64KB, 512KB, and 4MB and the whole thing was implemented in FreeBSD. He also described the techiques used for promoting and demoting superpages (i.e., automatically converting beween different page sizes as needed). He didn't even talk about other advantages of using superpages (e.g., for supporting large blocks), but the results he obtained were still impressive. BTW, another side effect of using superpages is that you tend to get better cache utilization because you automatically get a cache coloring effect by using the larger page sizes.
 Navarro et al., "Practical, transparent operating system support for superpages", OSDI '02.
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