From patchwork Wed Dec 26 13:14:59 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fengguang Wu X-Patchwork-Id: 10743121 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0B6F891E for ; Wed, 26 Dec 2018 13:38:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E8ECF28495 for ; Wed, 26 Dec 2018 13:38:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DCD5028938; Wed, 26 Dec 2018 13:38:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 92CC228495 for ; Wed, 26 Dec 2018 13:38:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727128AbeLZNh6 (ORCPT ); Wed, 26 Dec 2018 08:37:58 -0500 Received: from mga06.intel.com ([134.134.136.31]:21293 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726994AbeLZNhH (ORCPT ); Wed, 26 Dec 2018 08:37:07 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Dec 2018 05:37:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,400,1539673200"; d="scan'208";a="113358941" Received: from wangdan1-mobl1.ccr.corp.intel.com (HELO wfg-t570.sh.intel.com) ([10.254.210.154]) by orsmga003.jf.intel.com with ESMTP; 26 Dec 2018 05:37:02 -0800 Received: from wfg by wfg-t570.sh.intel.com with local (Exim 4.89) (envelope-from ) id 1gc9Mr-0005Ot-GK; Wed, 26 Dec 2018 21:37:01 +0800 Message-Id: <20181226133351.828074959@intel.com> User-Agent: quilt/0.65 Date: Wed, 26 Dec 2018 21:14:59 +0800 From: Fengguang Wu To: Andrew Morton cc: Linux Memory Management List , Jingqi Liu , Fengguang Wu cc: kvm@vger.kernel.org Cc: LKML cc: Fan Du cc: Yao Yuan cc: Peng Dong cc: Huang Ying cc: Dong Eddie cc: Dave Hansen cc: Zhang Yi cc: Dan Williams Subject: [RFC][PATCH v2 13/21] x86/pgtable: dont check PMD accessed bit References: <20181226131446.330864849@intel.com> MIME-Version: 1.0 Content-Disposition: inline; filename=0006-pgtable-don-t-check-the-page-accessed-bit.patch Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Jingqi Liu ept-idle will clear PMD accessed bit to speedup PTE scan -- if the bit remains unset in the next scan, all the 512 PTEs can be skipped. So don't complain on !_PAGE_ACCESSED in pmd_bad(). Note that clearing PMD accessed bit has its own cost, the optimization may only be worthwhile for - large idle area - sparsely populated area Signed-off-by: Jingqi Liu Signed-off-by: Fengguang Wu --- arch/x86/include/asm/pgtable.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- linux.orig/arch/x86/include/asm/pgtable.h 2018-12-23 19:50:50.917902600 +0800 +++ linux/arch/x86/include/asm/pgtable.h 2018-12-23 19:50:50.913902605 +0800 @@ -821,7 +821,8 @@ static inline pte_t *pte_offset_kernel(p static inline int pmd_bad(pmd_t pmd) { - return (pmd_flags(pmd) & ~_PAGE_USER) != _KERNPG_TABLE; + return (pmd_flags(pmd) & ~(_PAGE_USER | _PAGE_ACCESSED)) != + (_KERNPG_TABLE & ~_PAGE_ACCESSED); } static inline unsigned long pages_to_mb(unsigned long npg)