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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 568B6C433EF for ; Fri, 18 Mar 2022 01:01:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C06798D0002; Thu, 17 Mar 2022 21:01:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B9AB88D0001; Thu, 17 Mar 2022 21:01:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A2EA78D0002; Thu, 17 Mar 2022 21:01:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 911728D0001 for ; Thu, 17 Mar 2022 21:01:39 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 565D824A2E for ; Fri, 18 Mar 2022 01:01:39 +0000 (UTC) X-FDA: 79255704318.03.427AEEE Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by imf10.hostedemail.com (Postfix) with ESMTP id 3506DC0015 for ; Fri, 18 Mar 2022 01:01:35 +0000 (UTC) Received: from [10.20.42.25] (unknown [10.20.42.25]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9BxwM7t2TNiWz4LAA--.32529S3; Fri, 18 Mar 2022 09:01:33 +0800 (CST) Subject: Re: [PATCH v2] mm: add access/dirty bit on numa page fault To: Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Anshuman Khandual References: <20220317065033.2635123-1-maobibo@loongson.cn> From: maobibo Message-ID: Date: Fri, 18 Mar 2022 09:01:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CM-TRANSID:AQAAf9BxwM7t2TNiWz4LAA--.32529S3 X-Coremail-Antispam: 1UD129KBjvJXoW7Cr15uFyDZr13trWrZw4fXwb_yoW5JF47pF Z5CayYqFsrXr18AwsrGw1qyr1rXa48KFy3Cr9rta4Utws8urn7uryUW3yF9aykCry8tw4D Jr4UWFWUua90q3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvIb7Iv0xC_Kw4lb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4 vEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40E FcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr 0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxk0xIA0c2IEe2xFo4CEbIxv r21lc2xSY4AK6svPMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I 0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWU AVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcV CY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv 67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf 9x07bOoGdUUUUU= X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3506DC0015 X-Stat-Signature: d9cnxdc4tnycqx6pbajy6x459ab47fga Authentication-Results: imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of maobibo@loongson.cn designates 114.242.206.163 as permitted sender) smtp.mailfrom=maobibo@loongson.cn; dmarc=none X-Rspam-User: X-HE-Tag: 1647565295-588338 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 03/17/2022 08:23 PM, Matthew Wilcox wrote: > On Thu, Mar 17, 2022 at 02:50:33AM -0400, Bibo Mao wrote: >> On platforms like x86/arm which supports hw page walking, access >> and dirty bit is set by hw, however on some platforms without >> such hw functions, access and dirty bit is set by software in >> next trap. >> >> During numa page fault, dirty bit can be added for old pte if >> fail to migrate on write fault. And if it succeeds to migrate, >> access bit can be added for migrated new pte, also dirty bit >> can be added for write fault. > > Is this a correctness problem, in which case this will need to be > backported, or is this a performance problem, in which case can you > share some numbers? It is only performance issue, and there is no obvious performance improvement for general workloads on my hand, but I do not test it on microbenchmark. > >> Signed-off-by: Bibo Mao >> --- >> mm/memory.c | 21 ++++++++++++++++++++- >> 1 file changed, 20 insertions(+), 1 deletion(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index c125c4969913..65813bec9c06 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -4404,6 +4404,22 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) >> if (migrate_misplaced_page(page, vma, target_nid)) { >> page_nid = target_nid; >> flags |= TNF_MIGRATED; >> + >> + /* >> + * update pte entry with access bit, and dirty bit for >> + * write fault >> + */ >> + spin_lock(vmf->ptl); >> + pte = *vmf->pte; >> + pte = pte_mkyoung(pte); >> + if (was_writable) { >> + pte = pte_mkwrite(pte); >> + if (vmf->flags & FAULT_FLAG_WRITE) >> + pte = pte_mkdirty(pte); >> + } >> + set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); >> + update_mmu_cache(vma, vmf->address, vmf->pte); >> + pte_unmap_unlock(vmf->pte, vmf->ptl); >> } else { >> flags |= TNF_MIGRATE_FAIL; >> vmf->pte = pte_offset_map(vmf->pmd, vmf->address); >> @@ -4427,8 +4443,11 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) >> old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte); >> pte = pte_modify(old_pte, vma->vm_page_prot); >> pte = pte_mkyoung(pte); >> - if (was_writable) >> + if (was_writable) { >> pte = pte_mkwrite(pte); >> + if (vmf->flags & FAULT_FLAG_WRITE) >> + pte = pte_mkdirty(pte); >> + } >> ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte); >> update_mmu_cache(vma, vmf->address, vmf->pte); >> pte_unmap_unlock(vmf->pte, vmf->ptl); >> -- >> 2.31.1 >> >>