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=-9.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 229B5C433E0 for ; Wed, 27 Jan 2021 17:00:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3C5064DA2 for ; Wed, 27 Jan 2021 17:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234229AbhA0RA1 (ORCPT ); Wed, 27 Jan 2021 12:00:27 -0500 Received: from smtp-fw-9101.amazon.com ([207.171.184.25]:18732 "EHLO smtp-fw-9101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234192AbhA0Q5z (ORCPT ); Wed, 27 Jan 2021 11:57:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1611766675; x=1643302675; h=from:to:cc:subject:date:message-id:in-reply-to: mime-version; bh=i5zluJQ8Ep7MHqr2mjA7/P86f9akCWCX+vhcFXDo1AU=; b=JMUVhCBndDaSn1y7adHTCK8wAbUfbFbi8KFDlT5kQwRB3zN3Vvfclzve 9sQDaS57ZhZdJX5O8254NIVoiwBL7u37EUnw2dEim3U+0wqMUzmCH+nAH KewWxaN7vZymBhUcnUyRv4p9z0MjR/dOMsGXMzyop/DDHvG3WZCTixI3U 0=; X-IronPort-AV: E=Sophos;i="5.79,380,1602547200"; d="scan'208";a="106835424" Received: from sea3-co-svc-lb6-vlan2.sea.amazon.com (HELO email-inbound-relay-2b-8cc5d68b.us-west-2.amazon.com) ([10.47.22.34]) by smtp-border-fw-out-9101.sea19.amazon.com with ESMTP; 27 Jan 2021 16:57:08 +0000 Received: from EX13D31EUA001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-2b-8cc5d68b.us-west-2.amazon.com (Postfix) with ESMTPS id 6986AA18C3; Wed, 27 Jan 2021 16:57:05 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.160.132) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 27 Jan 2021 16:56:48 +0000 From: SeongJae Park To: SeongJae Park CC: Shakeel Butt , , "Andrea Arcangeli" , , , , , , Brendan Higgins , Qian Cai , Colin Ian King , Jonathan Corbet , "David Hildenbrand" , , Marco Elver , "Du, Fan" , , "Greg Thelen" , Ian Rogers , , "Kirill A. Shutemov" , Mark Rutland , Mel Gorman , Minchan Kim , Ingo Molnar , , "Peter Zijlstra (Intel)" , Randy Dunlap , Rik van Riel , David Rientjes , Steven Rostedt , Mike Rapoport , , Shuah Khan , , , Vlastimil Babka , Vladimir Davydov , Yang Shi , Huang Ying , , , Linux MM , , LKML Subject: Re: [PATCH v23 05/15] mm/damon: Implement primitives for the virtual memory address spaces Date: Wed, 27 Jan 2021 17:56:30 +0100 Message-ID: <20210127165630.29904-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201224071111.11551-1-sjpark@amazon.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.160.132] X-ClientProxiedBy: EX13D28UWC004.ant.amazon.com (10.43.162.24) To EX13D31EUA001.ant.amazon.com (10.43.165.15) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 24 Dec 2020 08:11:11 +0100 SeongJae Park wrote: > On Wed, 23 Dec 2020 14:54:02 -0800 Shakeel Butt wrote: > > > On Wed, Dec 23, 2020 at 8:47 AM SeongJae Park wrote: > > > > > [snip] > > > > [snip] > > > > > + > > > > > +static bool damon_va_young(struct mm_struct *mm, unsigned long addr, > > > > > + unsigned long *page_sz) > > > > > +{ > > > > > + pte_t *pte = NULL; > > > > > + pmd_t *pmd = NULL; > > > > > + spinlock_t *ptl; > > > > > + bool young = false; > > > > > + > > > > > + if (follow_pte_pmd(mm, addr, NULL, &pte, &pmd, &ptl)) > > > > > + return false; > > > > > + > > > > > + *page_sz = PAGE_SIZE; > > > > > + if (pte) { > > > > > + young = pte_young(*pte); > > > > > + if (!young) > > > > > + young = !page_is_idle(pte_page(*pte)); > > > > > + pte_unmap_unlock(pte, ptl); > > > > > + return young; > > > > > + } > > > > > + > > > > > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > > > > > + young = pmd_young(*pmd); > > > > > + if (!young) > > > > > + young = !page_is_idle(pmd_page(*pmd)); > > > > > + spin_unlock(ptl); > > > > > + *page_sz = ((1UL) << HPAGE_PMD_SHIFT); > > > > > +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > > > > > + > > > > > + return young; > > > > > > > > You need mmu_notifier_test_young() here. Hmm I remember mentioning > > > > this in some previous version as well. > > > > > > Your question and my answer was as below: > > > > > > > Don't you need mmu_notifier_clear_young() here? > > > > > > I think we don't need it here because we only read the Accessed bit and PG_Idle > > > if Accessed bit was not set. > > > > > > I should notice that you mean 'test_young()' but didn't, sorry. I will add it > > > in the next version. > > > > > > > I should have said mmu_notifier_test_young() instead of > > mmu_notifier_clear_young(). > > > > > > > > > > BTW have you tested this on a VM? > > > > > > Yes. Indeed, I'm testing this on a QEMU/KVM environment. You can get more > > > detail at: https://damonitor.github.io/doc/html/latest/vm/damon/eval.html#setup > > > > > > > Hmm without mmu_notifier_test_young() you should be missing the kvm > > mmu access updates. Can you please recheck if your eval is correctly > > seeing the memory accesses from the VM? > > Seems I didn't clearly answered, sorry. My test setup installs the > DAMON-enabled kernel in a guest VM and run it for workloads in the guest, > rather than running DAMON in host to monitor accesses of VMs. The MMU notifier > is for latter case, AFAIU, so my test setup didn't see the problem. Just FYI. I confirmed the mmu_notifier_test_young() added version works for the use case. I tested it by running a program accessing 200MB memory in a QEMU/KVM guest having 120GB memory and monitoring the qemu process' virtual address space from the host using DAMON. The 200MB memory region was clearly identifiable. Thanks, SeongJae Park