On 05/17/2012 05:09 AM, Peter Zijlstra wrote: > On Wed, 2012-05-16 at 21:34 +0800, Alex Shi wrote: >> >> So, if the minimum change of tlb->start/end can be protected by >> HAVE_GENERIC_MMU_GATHER, it is safe and harmless, am I right? >> > safe yes, but not entirely harmless. A quick look seems to suggest you > fail for VM_HUGETLB. If your mmu_gather spans a vma with VM_HUGETLB > you'll do a regular range flush not a full mm flush like the other paths > do. Thanks! Uh, HUGETLB will be found by has_large_page() if THP enabled now. And I will remove THP cost, then HUGETLB will be deal well. Since the max number of TLB entries is 512, has_large_page just need execute once just when the start address is align at HPAGE_SIZE. IMHO, this patch enabled generic mmu range flush support with just teen lines. and it is supported well by low level x86 architecture. I like it. :) > > Anyway, I did a quick refresh of my series on a recent -tip tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/mmu.git tlb-unify > > With that all you need is to "select HAVE_MMU_GATHER_RANGE" for x86 and > implement a useful flush_tlb_range(). > > In particular, see: > http://git.kernel.org/?p=linux/kernel/git/peterz/mmu.git;a=commitdiff;h=05e53144177e6242fda404045f50f48114bcf185;hp=2cd7dc710652127522392f4b7ecb5fa6e954941e > > I've slightly changed the code to address an open issue with the > vm_flags tracking. We now force flush the mmu_gather whenever VM_HUGETLB > flips because most (all?) archs that look at that flag expect pure huge > pages and not a mixture. > > I've seem to have misplaced my cross-compiler set, so I've only compiled > x86-64 for now. Oh, I also need a cross-compiler for other archs. Thanks reminder! -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
