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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 877B7C433E5 for ; Sat, 18 Jul 2020 02:52:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3CE6F2070E for ; Sat, 18 Jul 2020 02:52:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="u69SZ41F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3CE6F2070E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DAB448D0009; Fri, 17 Jul 2020 22:52:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D80D36B0092; Fri, 17 Jul 2020 22:52:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C6F308D0009; Fri, 17 Jul 2020 22:52:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id AF4836B008C for ; Fri, 17 Jul 2020 22:52:57 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 6D3AF8248047 for ; Sat, 18 Jul 2020 02:52:57 +0000 (UTC) X-FDA: 77049674394.06.cow72_330df0826f10 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id 9D20F10064D06 for ; Sat, 18 Jul 2020 02:52:41 +0000 (UTC) X-HE-Tag: cow72_330df0826f10 X-Filterd-Recvd-Size: 10392 Received: from smtp-fw-9102.amazon.com (smtp-fw-9102.amazon.com [207.171.184.29]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Sat, 18 Jul 2020 02:52:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1595040762; x=1626576762; h=from:to:cc:subject:date:message-id:in-reply-to: mime-version; bh=/6JkoobPwF5BrmIAwJMq4G3QuiQzdD9VSEAmA33e7wo=; b=u69SZ41Fm1WC8lsT3Wc2XWn61gRaAj8vRj0pEPKh0uFarOjk1hTtUvpA AIKyu9SA2RED+v7RJlQHrVuGLhMsMz5bQU0bTUAhpKaRNeeOPWJe6uE8n pk8aeHOYzin7V4k9eus5xTXEgmTnZb9yHT+pMuuQ5ktaOgwj5iyMvAvfN A=; IronPort-SDR: Vdl0QXsFVg6JMMLvM5eqebj1Y0+Jo9ZZ0lWpw7ngv40B4EPDpMa+8G/801KD/YBEUld6lRn58V DD40WAsSFUcA== X-IronPort-AV: E=Sophos;i="5.75,365,1589241600"; d="scan'208";a="60742406" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2b-4ff6265a.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 18 Jul 2020 02:52:37 +0000 Received: from EX13MTAUEA002.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2b-4ff6265a.us-west-2.amazon.com (Postfix) with ESMTPS id EDE25A279C; Sat, 18 Jul 2020 02:52:34 +0000 (UTC) Received: from EX13D31EUA004.ant.amazon.com (10.43.165.161) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 18 Jul 2020 02:52:34 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.162.140) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 18 Jul 2020 02:52:18 +0000 From: SeongJae Park To: Shakeel Butt CC: SeongJae Park , Andrew Morton , SeongJae Park , , Andrea Arcangeli , , , , , , Brendan Higgins , Qian Cai , Colin Ian King , Jonathan Corbet , "David Hildenbrand" , , , Ian Rogers , , "Kirill A. Shutemov" , , Mel Gorman , Minchan Kim , Ingo Molnar , , "Peter Zijlstra (Intel)" , Randy Dunlap , Rik van Riel , David Rientjes , Steven Rostedt , , , , , , Vlastimil Babka , Vladimir Davydov , Yang Shi , Huang Ying , , Linux MM , , LKML Subject: Re: Re: Re: Re: [PATCH v18 06/14] mm/damon: Implement callbacks for the virtual memory address spaces Date: Sat, 18 Jul 2020 04:51:58 +0200 Message-ID: <20200718025158.771-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: (raw) MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.162.140] X-ClientProxiedBy: EX13D13UWB002.ant.amazon.com (10.43.161.21) To EX13D31EUA004.ant.amazon.com (10.43.165.161) X-Rspamd-Queue-Id: 9D20F10064D06 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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 Fri, 17 Jul 2020 19:23:28 -0700 Shakeel Butt wrote: > On Fri, Jul 17, 2020 at 9:24 AM SeongJae Park wrote: > > > > On Fri, 17 Jul 2020 08:17:09 -0700 Shakeel Butt wrote: > > > > > On Thu, Jul 16, 2020 at 11:54 PM SeongJae Park wrote: > > > > > > > > On Thu, 16 Jul 2020 17:46:54 -0700 Shakeel Butt wrote: > > > > > > > > > On Mon, Jul 13, 2020 at 1:44 AM SeongJae Park wrote: > > > > > > > > > > > > From: SeongJae Park > > > > > > > > > > > > This commit introduces a reference implementation of the address space > > > > > > specific low level primitives for the virtual address space, so that > > > > > > users of DAMON can easily monitor the data accesses on virtual address > > > > > > spaces of specific processes by simply configuring the implementation to > > > > > > be used by DAMON. > > > > > > > > > > > > The low level primitives for the fundamental access monitoring are > > > > > > defined in two parts: > > > > > > 1. Identification of the monitoring target address range for the address > > > > > > space. > > > > > > 2. Access check of specific address range in the target space. > > > > > > > > > > > > The reference implementation for the virtual address space provided by > > > > > > this commit is designed as below. > > > > > > > > > > > > PTE Accessed-bit Based Access Check > > > > > > ----------------------------------- > > > > > > > > > > > > The implementation uses PTE Accessed-bit for basic access checks. That > > > > > > is, it clears the bit for next sampling target page and checks whether > > > > > > it set again after one sampling period. To avoid disturbing other > > > > > > Accessed bit users such as the reclamation logic, the implementation > > > > > > adjusts the ``PG_Idle`` and ``PG_Young`` appropriately, as same to the > > > > > > 'Idle Page Tracking'. > > > > > > > > > > > > VMA-based Target Address Range Construction > > > > > > ------------------------------------------- > > > > > > > > > > > > Only small parts in the super-huge virtual address space of the > > > > > > processes are mapped to physical memory and accessed. Thus, tracking > > > > > > the unmapped address regions is just wasteful. However, because DAMON > > > > > > can deal with some level of noise using the adaptive regions adjustment > > > > > > mechanism, tracking every mapping is not strictly required but could > > > > > > even incur a high overhead in some cases. That said, too huge unmapped > > > > > > areas inside the monitoring target should be removed to not take the > > > > > > time for the adaptive mechanism. > > > > > > > > > > > > For the reason, this implementation converts the complex mappings to > > > > > > three distinct regions that cover every mapped area of the address > > > > > > space. Also, the two gaps between the three regions are the two biggest > > > > > > unmapped areas in the given address space. The two biggest unmapped > > > > > > areas would be the gap between the heap and the uppermost mmap()-ed > > > > > > region, and the gap between the lowermost mmap()-ed region and the stack > > > > > > in most of the cases. Because these gaps are exceptionally huge in > > > > > > usual address spacees, excluding these will be sufficient to make a > > > > > > reasonable trade-off. Below shows this in detail:: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > (small mmap()-ed regions and munmap()-ed regions) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: SeongJae Park > > > > > > Reviewed-by: Leonard Foerster > > > > > [snip] > > > > > > + > > > > > > +static void damon_mkold(struct mm_struct *mm, unsigned long addr) > > > > > > +{ > > > > > > + pte_t *pte = NULL; > > > > > > + pmd_t *pmd = NULL; > > > > > > + spinlock_t *ptl; > > > > > > + > > > > > > + if (follow_pte_pmd(mm, addr, NULL, &pte, &pmd, &ptl)) > > > > > > + return; > > > > > > + > > > > > > + if (pte) { > > > > > > + if (pte_young(*pte)) { > > > > > > > > > > Any reason for skipping mmu_notifier_clear_young()? Why exclude VMs as > > > > > DAMON's target applications? > > > > > > > > Obviously my mistake, thank you for pointing this! I will add the function > > > > call in the next spin. > > > > > > > > > > Similarly mmu_notifier_test_young() for the damon_young(). > > > > Yes, indeed. Thanks for pointing this, either :) > > > > > BTW I think we can combine ctx->prepare_access_checks() and > > > ctx->check_accesses() into one i.e. get the young state for the previous > > > cycle and mkold for the next cycle in a single step. > > > > Yes, we could. But, I'm unsure what is the advantage of doing that. First of > > all, if the combined implementation is required, peopld could simply implement > > the two logics in the combined way in one of the callbacks and leave the other > > one blank. Also, I'm worrying if combining those could make the code a little > > bit hard to read. IMHO, I think separating those makes the 'kdamond_fn()' code > > little bit easier to read. Actually, I started from the combined approach but > > separated the two logics since v7 after Jonathan's comment[1]. > > > > > > [1] https://lore.kernel.org/linux-mm/20200310085721.00000a0f@Huawei.com/ > > > > > > > > > > I am wondering if there is any advantage to having "Page Idle > > > Tracking" beside DAMON. I think we can make them mutually exclusive. > > > Once we have established that I think DAMON can steal the two page > > > flag bits from it and can make use of them. What do you think? > > > > Again, yes, I think we could. But I don't see clear advantage of it for now. > > > > > > Hmm, I will think more about it. Somehow I feel if we want to monitor > at the page sized region granularity then this will be really helpful. > Anyways, it needs more brainstorming. Ok, I will also think about it from the perspective. > > BTW I am still going over the series and my humble request would be to > wait till I have gone through the series completely and provided the > feedback then you can send the next version after incorporating the > feedback. No problem, just let me know when you finished. Appreciate your review :) Thanks, SeongJae Park > > Shakeel >