Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753111AbaDDNUz (ORCPT ); Fri, 4 Apr 2014 09:20:55 -0400 Received: from mta-out.inet.fi ([195.156.147.13]:60522 "EHLO jenni1.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752700AbaDDNUw (ORCPT ); Fri, 4 Apr 2014 09:20:52 -0400 Date: Fri, 4 Apr 2014 16:17:47 +0300 From: "Kirill A. Shutemov" To: Madhavan Srinivasan Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, benh@kernel.crashing.org, paulus@samba.org, kirill.shutemov@linux.intel.com, rusty@rustcorp.com.au, akpm@linux-foundation.org, riel@redhat.com, mgorman@suse.de, ak@linux.intel.com, peterz@infradead.org, mingo@kernel.org Subject: Re: [PATCH V2 1/2] mm: move FAULT_AROUND_ORDER to arch/ Message-ID: <20140404131747.GA23076@node.dhcp.inet.fi> References: <1396592835-24767-1-git-send-email-maddy@linux.vnet.ibm.com> <1396592835-24767-2-git-send-email-maddy@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396592835-24767-2-git-send-email-maddy@linux.vnet.ibm.com> User-Agent: Mutt/1.5.22.1-rc1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 04, 2014 at 11:57:14AM +0530, Madhavan Srinivasan wrote: > Kirill A. Shutemov with faultaround patchset introduced > vm_ops->map_pages() for mapping easy accessible pages around > fault address in hope to reduce number of minor page faults. > > This patch creates infrastructure to move the FAULT_AROUND_ORDER > to arch/ using Kconfig. This will enable architecture maintainers > to decide on suitable FAULT_AROUND_ORDER value based on > performance data for that architecture. Patch also adds > FAULT_AROUND_ORDER Kconfig element in arch/X86. > > Signed-off-by: Madhavan Srinivasan > --- > arch/x86/Kconfig | 4 ++++ > include/linux/mm.h | 9 +++++++++ > mm/memory.c | 12 +++++------- > 3 files changed, 18 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 9c0a657..5833f22 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1177,6 +1177,10 @@ config DIRECT_GBPAGES > support it. This can improve the kernel's performance a tiny bit by > reducing TLB pressure. If in doubt, say "Y". > > +config FAULT_AROUND_ORDER > + int > + default "4" > + > # Common NUMA Features > config NUMA > bool "Numa Memory Allocation and Scheduler Support" > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 0bd4359..b93c1c3 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -26,6 +26,15 @@ struct file_ra_state; > struct user_struct; > struct writeback_control; > > +/* > + * Fault around order is a control knob to decide the fault around pages. > + * Default value is set to 0UL (disabled), but the arch can override it as > + * desired. > + */ > +#ifndef CONFIG_FAULT_AROUND_ORDER > +#define CONFIG_FAULT_AROUND_ORDER 0 > +#endif > + I don't think it should be in header file: nobody except mm/memory.c cares. Just put it instead '#define FAULT_AROUND_ORDER'. > #ifndef CONFIG_NEED_MULTIPLE_NODES /* Don't use mapnrs, do it properly */ > extern unsigned long max_mapnr; > > diff --git a/mm/memory.c b/mm/memory.c > index b02c584..22a4a89 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3358,10 +3358,8 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, > update_mmu_cache(vma, address, pte); > } > > -#define FAULT_AROUND_ORDER 4 > - > #ifdef CONFIG_DEBUG_FS > -static unsigned int fault_around_order = FAULT_AROUND_ORDER; > +static unsigned int fault_around_order = CONFIG_FAULT_AROUND_ORDER; > > static int fault_around_order_get(void *data, u64 *val) > { > @@ -3371,7 +3369,7 @@ static int fault_around_order_get(void *data, u64 *val) > > static int fault_around_order_set(void *data, u64 val) > { > - BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE); > + BUILD_BUG_ON((1UL << CONFIG_FAULT_AROUND_ORDER) > PTRS_PER_PTE); > if (1UL << val > PTRS_PER_PTE) > return -EINVAL; > fault_around_order = val; > @@ -3406,14 +3404,14 @@ static inline unsigned long fault_around_pages(void) > { > unsigned long nr_pages; > > - nr_pages = 1UL << FAULT_AROUND_ORDER; > + nr_pages = 1UL << CONFIG_FAULT_AROUND_ORDER; > BUILD_BUG_ON(nr_pages > PTRS_PER_PTE); > return nr_pages; > } > > static inline unsigned long fault_around_mask(void) > { > - return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1); > + return ~((1UL << (PAGE_SHIFT + CONFIG_FAULT_AROUND_ORDER)) - 1); > } > #endif > > @@ -3471,7 +3469,7 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, > * if page by the offset is not ready to be mapped (cold cache or > * something). > */ > - if (vma->vm_ops->map_pages) { > + if ((vma->vm_ops->map_pages) && (fault_around_pages() > 1)) { if (vma->vm_ops->map_pages && fault_around_pages()) { > pte = pte_offset_map_lock(mm, pmd, address, &ptl); > do_fault_around(vma, address, pte, pgoff, flags); > if (!pte_same(*pte, orig_pte)) > -- > 1.7.10.4 > > -- > 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/ -- Kirill A. Shutemov -- 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/