Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752915AbbGVVjj (ORCPT ); Wed, 22 Jul 2015 17:39:39 -0400 Received: from mail-pa0-f44.google.com ([209.85.220.44]:35745 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681AbbGVVjh (ORCPT ); Wed, 22 Jul 2015 17:39:37 -0400 Date: Wed, 22 Jul 2015 14:39:34 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Catalin Marinas cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Andrea Arcangeli Subject: Re: [PATCH] mm: Flush the TLB for a single address in a huge page In-Reply-To: <1437585214-22481-1-git-send-email-catalin.marinas@arm.com> Message-ID: References: <1437585214-22481-1-git-send-email-catalin.marinas@arm.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3175 Lines: 83 On Wed, 22 Jul 2015, Catalin Marinas wrote: > When the page table entry is a huge page (and not a table), there is no > need to flush the TLB by range. This patch changes flush_tlb_range() to > flush_tlb_page() in functions where we know the pmd entry is a huge > page. > > Signed-off-by: Catalin Marinas > Cc: Andrew Morton > Cc: Andrea Arcangeli > --- > > Hi, > > That's just a minor improvement but it saves iterating over each small > page in a huge page when a single TLB entry is used (we already have a > similar assumption in __tlb_adjust_range). > For x86 smp, this seems to mean the difference between unconditional flush_tlb_page() and local_flush_tlb() due to tlb_single_page_flush_ceiling, so I don't think this just removes the iteration. > Thanks. > > mm/pgtable-generic.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c > index 6b674e00153c..ff17eca26211 100644 > --- a/mm/pgtable-generic.c > +++ b/mm/pgtable-generic.c > @@ -67,7 +67,7 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > if (changed) { > set_pmd_at(vma->vm_mm, address, pmdp, entry); > - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > + flush_tlb_page(vma, address); > } > return changed; > #else /* CONFIG_TRANSPARENT_HUGEPAGE */ > @@ -101,7 +101,7 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma, > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > young = pmdp_test_and_clear_young(vma, address, pmdp); > if (young) > - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > + flush_tlb_page(vma, address); > return young; > } > #endif > @@ -128,7 +128,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > VM_BUG_ON(!pmd_trans_huge(*pmdp)); > pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); > - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > + flush_tlb_page(vma, address); > return pmd; > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > @@ -143,7 +143,7 @@ void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > set_pmd_at(vma->vm_mm, address, pmdp, pmd); > /* tlb flush only to serialize against gup-fast */ > - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > + flush_tlb_page(vma, address); > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > #endif > @@ -195,7 +195,7 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, > { > pmd_t entry = *pmdp; > set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry)); > - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); > + flush_tlb_page(vma, address); > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/