From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0C5FC433E0 for ; Wed, 20 May 2020 08:22:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 97EB82065F for ; Wed, 20 May 2020 08:22:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97EB82065F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 491D580007; Wed, 20 May 2020 04:22:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4696C900002; Wed, 20 May 2020 04:22:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3A73680007; Wed, 20 May 2020 04:22:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0064.hostedemail.com [216.40.44.64]) by kanga.kvack.org (Postfix) with ESMTP id 2452D900002 for ; Wed, 20 May 2020 04:22:49 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D4A37181AEF32 for ; Wed, 20 May 2020 08:22:48 +0000 (UTC) X-FDA: 76836406416.14.tank43_8cc73269a535b X-HE-Tag: tank43_8cc73269a535b X-Filterd-Recvd-Size: 5093 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Wed, 20 May 2020 08:22:47 +0000 (UTC) Received: from [10.20.42.25] (unknown [10.20.42.25]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9DxP2jB6MReLuc2AA--.129S3; Wed, 20 May 2020 16:22:26 +0800 (CST) Subject: Re: [PATCH v4 3/4] mm/memory.c: Add memory read privilege on page fault handling To: Andrew Morton References: <1589882610-7291-1-git-send-email-maobibo@loongson.cn> <1589882610-7291-3-git-send-email-maobibo@loongson.cn> <20200519183035.14fc56ba957266dde87a7778@linux-foundation.org> Cc: Thomas Bogendoerfer , Jiaxun Yang , Huacai Chen , Paul Burton , Dmitry Korotin , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Stafford Horne , Steven Price , Anshuman Khandual , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Rapoport , Sergei Shtylyov , "Maciej W. Rozycki" , linux-mm@kvack.org, David Hildenbrand From: maobibo Message-ID: <55379391-7c1f-7d0e-773e-d44fa95e0e24@loongson.cn> Date: Wed, 20 May 2020 16:22:25 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20200519183035.14fc56ba957266dde87a7778@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-CM-TRANSID:AQAAf9DxP2jB6MReLuc2AA--.129S3 X-Coremail-Antispam: 1UD129KBjvJXoW7CF4DtF1fWF4rKFyxJr1fWFg_yoW8ury7pF ykCF1jvF4DJr17AFyxGws7ur1fC3yfKFsrurn3KryDC3Z8JrnYgrs7JayYgFy8GF4jv3Wr Ar4qqFZ8ZanFvaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvEb7Iv0xC_Kw4lb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4 vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvEwIxGrwACI402YVCY1x02628vn2kIc2xK xwCYjI0SjxkI62AI1cAE67vIY487MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r 1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CE b7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0x vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI 42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWI evJa73UjIFyTuYvjxUg0D7DUUUU X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 05/20/2020 09:30 AM, Andrew Morton wrote: > On Tue, 19 May 2020 18:03:29 +0800 Bibo Mao wrote: > >> Here add pte_sw_mkyoung function to make page readable on MIPS >> platform during page fault handling. This patch improves page >> fault latency about 10% on my MIPS machine with lmbench >> lat_pagefault case. >> >> It is noop function on other arches, there is no negative >> influence on those architectures. >> >> --- a/arch/mips/include/asm/pgtable.h >> +++ b/arch/mips/include/asm/pgtable.h >> @@ -414,6 +414,8 @@ static inline pte_t pte_mkyoung(pte_t pte) >> return pte; >> } >> >> +#define pte_sw_mkyoung pte_mkyoung >> + >> #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT >> static inline int pte_huge(pte_t pte) { return pte_val(pte) & _PAGE_HUGE; } >> >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -227,6 +227,21 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres >> } >> #endif >> >> +/* >> + * On some architectures hardware does not set page access bit when accessing >> + * memory page, it is responsibilty of software setting this bit. It brings >> + * out extra page fault penalty to track page access bit. For optimization page >> + * access bit can be set during all page fault flow on these arches. >> + * To be differentiate with macro pte_mkyoung, this macro is used on platforms >> + * where software maintains page access bit. >> + */ >> +#ifndef pte_sw_mkyoung >> +static inline pte_t pte_sw_mkyoung(pte_t pte) >> +{ >> + return pte; >> +} >> +#endif > > Yup, that's neat enough. Thanks for making this change. It looks like > all architectures include asm-generic/pgtable.h so that's fine. > > It's conventional to add a > > #define pte_sw_mkyoung pte_sw_mkyoung > > immediately above the #endif there, so we can't try to implement > pte_sw_mkyoung() twice if this header gets included twice. But the > header has #ifndef _ASM_GENERIC_PGTABLE_H around the whole thing so > that should be OK. Sure, will do, and thanks for your kindly help and guidance