On Sat, Jan 10, 2015 at 10:36:13PM +0100, Arnd Bergmann wrote: > On Saturday 10 January 2015 13:00:27 Linus Torvalds wrote: > > so I feel pretty confident in saying it won't happen. It's just too > > much of a bother, for little to no actual upside. It's likely a much > > better approach to try to instead use THP for anonymous mappings. > > arm64 already supports 2MB transparent hugepages. I guess it > wouldn't be too hard to change it so that an existing hugepage > on an anonymous mapping that gets split up into 4KB pages gets > split along 64KB boundaries with the contiguous mapping bit set.
What you are talking about is in fact multi-level transparent huge page support: you need to couple 4k pages into 64k to avoid breaking them apart by compactation or migration or whatever. That definetely would not make THP code simplier. > Having full support for multiple hugepage sizes (64KB, 2MB and 32MB > in case of ARM64 with 4KB PAGE_SIZE) would be even better and > probably negate any benefits of 64KB PAGE_SIZE, but requires more > changes to common mm code. > > Arnd -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
