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Date: Mon, 20 Dec 2010 15:47:00 -0800 From: Jeremy Fitzhardinge <jeremy@...p.org> To: "H. Peter Anvin" <hpa@...or.com> CC: the arch/x86 maintainers <x86@...nel.org>, "Xen-devel@...ts.xensource.com" <Xen-devel@...ts.xensource.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: [PATCH] x86: do pmd_populate with lazy mmu updates This allows the set_pmd to be batched with whatever setup paravirt_alloc_pte() needs to do. pmd_populate() is always called under the pagetable lock, so this is safe. With a corresponding change in the Xen-specific code, this allows the setup of a new pte page to be done with 1 hypercall rather than 3. This results in a 3-8% improvement in fork performance, depending on process size (more improvement on larger processes). I expect a similar improvement in time spent touching a virgin part of the address space. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com> diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h index 271de94..15e1153f 100644 --- a/arch/x86/include/asm/pgalloc.h +++ b/arch/x86/include/asm/pgalloc.h @@ -71,8 +71,10 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, { unsigned long pfn = page_to_pfn(pte); + arch_enter_lazy_mmu_mode(); paravirt_alloc_pte(mm, pfn); set_pmd(pmd, __pmd(((pteval_t)pfn << PAGE_SHIFT) | _PAGE_TABLE)); + arch_leave_lazy_mmu_mode(); } #define pmd_pgtable(pmd) pmd_page(pmd) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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