Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754574AbaD1JEh (ORCPT ); Mon, 28 Apr 2014 05:04:37 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:59192 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753989AbaD1JEb (ORCPT ); Mon, 28 Apr 2014 05:04:31 -0400 From: Madhavan Srinivasan To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org Cc: 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, dave.hansen@intel.com, Madhavan Srinivasan Subject: [PATCH V3 1/2] mm: move FAULT_AROUND_ORDER to arch/ Date: Mon, 28 Apr 2014 14:31:29 +0530 Message-Id: <1398675690-16186-2-git-send-email-maddy@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1398675690-16186-1-git-send-email-maddy@linux.vnet.ibm.com> References: <1398675690-16186-1-git-send-email-maddy@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14042809-7014-0000-0000-000004CE4417 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kirill A. Shutemov with 8c6e50b029 commit 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 modify the FAULT_AROUND_ORDER value using mm/Kconfig. This will enable architecture maintainers to decide on suitable FAULT_AROUND_ORDER value based on performance data for that architecture. Patch also defaults FAULT_AROUND_ORDER Kconfig element to 4. Signed-off-by: Madhavan Srinivasan --- mm/Kconfig | 8 ++++++++ mm/memory.c | 11 ++++------- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/mm/Kconfig b/mm/Kconfig index ebe5880..c7fc4f1 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -176,6 +176,14 @@ config MOVABLE_NODE config HAVE_BOOTMEM_INFO_NODE def_bool n +# +# Fault around order is a control knob to decide the fault around pages. +# Default value is set to 4 , but the arch can override it as desired. +# +config FAULT_AROUND_ORDER + int + default 4 + # eventually, we can have this option just 'select SPARSEMEM' config MEMORY_HOTPLUG bool "Allow for memory hot-add" diff --git a/mm/memory.c b/mm/memory.c index d0f0bef..457436d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3382,11 +3382,9 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, update_mmu_cache(vma, address, pte); } -#define FAULT_AROUND_ORDER 4 +unsigned int fault_around_order = CONFIG_FAULT_AROUND_ORDER; #ifdef CONFIG_DEBUG_FS -static unsigned int fault_around_order = FAULT_AROUND_ORDER; - static int fault_around_order_get(void *data, u64 *val) { *val = fault_around_order; @@ -3395,7 +3393,6 @@ 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); if (1UL << val > PTRS_PER_PTE) return -EINVAL; fault_around_order = val; @@ -3430,14 +3427,14 @@ static inline unsigned long fault_around_pages(void) { unsigned long nr_pages; - nr_pages = 1UL << FAULT_AROUND_ORDER; + nr_pages = 1UL << 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 + fault_around_order)) - 1); } #endif @@ -3495,7 +3492,7 @@ 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_order)) { 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/