From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261677AbVFFUdP (ORCPT ); Mon, 6 Jun 2005 16:33:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261664AbVFFUcn (ORCPT ); Mon, 6 Jun 2005 16:32:43 -0400 Received: from bay-bridge.veritas.com ([143.127.3.10]:42386 "EHLO MTVMIME03.enterprise.veritas.com") by vger.kernel.org with ESMTP id S261662AbVFFUCr (ORCPT ); Mon, 6 Jun 2005 16:02:47 -0400 Date: Mon, 6 Jun 2005 21:03:23 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Andrew Morton cc: Abhijit Karmarkar , Martin Schwidefsky , linux-kernel@vger.kernel.org Subject: [PATCH] msync: check pte dirty earlier Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-OriginalArrivalTime: 06 Jun 2005 20:02:23.0520 (UTC) FILETIME=[A7770A00:01C56AD2] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Abhijit Karmarkar It's common practice to msync a large address range regularly, in which often only a few ptes have actually been dirtied since the previous pass. sync_pte_range then goes much faster if it tests whether pte is dirty before locating and accessing each struct page cacheline; and it is hardly slowed by ptep_clear_flush_dirty repeating that test in the opposite case, when every pte actually is dirty. But beware, s390's pte_dirty always says false, since its dirty bit is kept in the storage key, located via the struct page address. So skip this optimization in its case: use a pte_maybe_dirty macro which just says true if page_test_and_clear_dirty is implemented. Signed-off-by: Abhijit Karmarkar Signed-off-by: Hugh Dickins --- include/asm-generic/pgtable.h | 3 +++ mm/msync.c | 2 ++ 2 files changed, 5 insertions(+) --- 2.6.12-rc6/include/asm-generic/pgtable.h 2005-05-25 18:09:09.000000000 +0100 +++ linux/include/asm-generic/pgtable.h 2005-06-04 20:41:55.000000000 +0100 @@ -125,6 +125,9 @@ static inline void ptep_set_wrprotect(st #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY #define page_test_and_clear_dirty(page) (0) +#define pte_maybe_dirty(pte) pte_dirty(pte) +#else +#define pte_maybe_dirty(pte) (1) #endif #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG --- 2.6.12-rc6/mm/msync.c 2005-05-25 18:09:21.000000000 +0100 +++ linux/mm/msync.c 2005-06-04 20:41:55.000000000 +0100 @@ -34,6 +34,8 @@ static void sync_pte_range(struct vm_are if (!pte_present(*pte)) continue; + if (!pte_maybe_dirty(*pte)) + continue; pfn = pte_pfn(*pte); if (!pfn_valid(pfn)) continue;