Andrew Morton wrote: > On Mon, 7 Oct 2013 16:54:02 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > > Alex Thorlton noticed that some massively threaded workloads work poorly, > > if THP enabled. This patchset fixes this by introducing split page table > > lock for PMD tables. hugetlbfs is not covered yet. > > > > This patchset is based on work by Naoya Horiguchi. > > I think I'll summarise the results thusly: > > : THP off, v3.12-rc2: 18.059261877 seconds time elapsed > : THP off, patched: 16.768027318 seconds time elapsed > : > : THP on, v3.12-rc2: 42.162306788 seconds time elapsed > : THP on, patched: 8.397885779 seconds time elapsed > : > : HUGETLB, v3.12-rc2: 47.574936948 seconds time elapsed > : HUGETLB, patched: 19.447481153 seconds time elapsed > > What sort of machines are we talking about here? Can mortals expect to > see such results on their hardware, or is this mainly on SGI nuttyware? I've tested on 4 socket Westmere: 40 cores / 80 threads. With 4 threads, I can see 8% improvement on THP. Nothing comparing to 36 times on Alex's 512 cores, but still... > I'm seeing very few reviewed-by's and acked-by's in here, which is a > bit surprising and disappointing for a large patchset at v5. Are you > sure none were missed? Peter looked through, but I haven't got any tags from him. > The new code is enabled only for x86. Why is this? x86 is the only hardware I have to test. > What must arch maintainers do to enable it? Have you any particular > suggestions, warnings etc to make their lives easier? The last patch is a good illustration what need to be done. It's very straight forward, I don't see any pitfalls. > I assume the patchset won't damage bisectability? If our bisecter has > only the first eight patches applied, the fact that > CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK cannot be enabled protects from > failures? Unless CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK defined, pmd_lockptr() will return mm->page_table_lock: we can convert code to new api stet-by-step without breaking anything. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>