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=-14.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 726B2C433E0 for ; Fri, 17 Jul 2020 00:47:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2A6972070E for ; Fri, 17 Jul 2020 00:47:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aDfBJa1h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2A6972070E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 879F66B006C; Thu, 16 Jul 2020 20:47:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 804116B0070; Thu, 16 Jul 2020 20:47:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 67EE78D0001; Thu, 16 Jul 2020 20:47:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0251.hostedemail.com [216.40.44.251]) by kanga.kvack.org (Postfix) with ESMTP id 4DEE16B006C for ; Thu, 16 Jul 2020 20:47:08 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id D864E8248D51 for ; Fri, 17 Jul 2020 00:47:07 +0000 (UTC) X-FDA: 77045728494.28.cats62_2e0a3f926f06 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id AF2C86D71 for ; Fri, 17 Jul 2020 00:47:07 +0000 (UTC) X-HE-Tag: cats62_2e0a3f926f06 X-Filterd-Recvd-Size: 7502 Received: from mail-lj1-f195.google.com (mail-lj1-f195.google.com [209.85.208.195]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Jul 2020 00:47:07 +0000 (UTC) Received: by mail-lj1-f195.google.com with SMTP id f5so10560968ljj.10 for ; Thu, 16 Jul 2020 17:47:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6naa2MqV7Ilc0GHL/Mq4CUNJ5DExO6g8I7ykNmCXYjM=; b=aDfBJa1hKKV7jQJMC4EkqGeKU8mOarpu+ZSU10Qpf+G9Nh3PYJhtHwujbuBCQmkOFu FuAeKE7ejE0Ik9kImelQWrHk10ad8cjgH+25v+6Jd6hSkNFZ2QlPHholWxXxQLpWXUmj D/SlOaorHGtk44E3bgOYqQ0Xgz6eKP6apjln5UL5IGgJQrbOSfubbuvXeSNmc0uOf0LO MSfrrLslmhd0BlMca3sw+twVNL9nHo53f5m/44P1VhHfsvwAqpYUqhfGYjq+zDCaAXNs oz7tDJ4BFehqSL3eHOS3BrxGZ5L6x3TkNZb8x3MxPNBMRDEeuWm2NqXm3BlAVGGnsPVL Vyxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6naa2MqV7Ilc0GHL/Mq4CUNJ5DExO6g8I7ykNmCXYjM=; b=cR36ccjsOfVPyfEsLVLcwZBnjLKAqJ14C4nNRdqiEssxdNDiddo1BcC8ChcarVyco7 VMqclELu34VVOXrJ4J/FtKnYYAK3DACQIMDeCbHpVEO0TrTcVGwY+1uNhDionHlMjLXQ klvwDvXjsMgGqZMupDkGHWd2jppLui7HlOpMtThRaCdk6ezD0C17QdpF8o2t/w/fqwtB pHsdJbsgwI3avjDgOWdLgtml5ft42BvdUBdqAsZW6KWoLIZ0898OsIdVqz9ocy0DmD+X AkJ9Az//D53/CWAMLcI83PY2k5qySJlCkqKdABDC93Ta77o3H1+mvyTwDj3dz0g4tsjP Z8eQ== X-Gm-Message-State: AOAM530ZPiC28vSsUyy5lWs7IjsXrmPkGs8aoQR810DVVe8wK5p672GZ sCfk1nJgnF/NQG5K/pwyU6BClkU9FFtst+zzaQ3iPA== X-Google-Smtp-Source: ABdhPJy3rYlU+dpnm7Lt/c63FWZZAeOBpx+inKVqb80XPOCe8YjQA1Wf+GJqtSBf5Q8oHJWJlhnh2uemHMSK3JqIe/U= X-Received: by 2002:a2e:9907:: with SMTP id v7mr3295592lji.347.1594946825212; Thu, 16 Jul 2020 17:47:05 -0700 (PDT) MIME-Version: 1.0 References: <20200713084144.4430-1-sjpark@amazon.com> <20200713084144.4430-7-sjpark@amazon.com> In-Reply-To: <20200713084144.4430-7-sjpark@amazon.com> From: Shakeel Butt Date: Thu, 16 Jul 2020 17:46:54 -0700 Message-ID: Subject: Re: [PATCH v18 06/14] mm/damon: Implement callbacks for the virtual memory address spaces To: SeongJae Park Cc: Andrew Morton , SeongJae Park , Jonathan.Cameron@huawei.com, Andrea Arcangeli , acme@kernel.org, alexander.shishkin@linux.intel.com, amit@kernel.org, benh@kernel.crashing.org, brendan.d.gregg@gmail.com, Brendan Higgins , Qian Cai , Colin Ian King , Jonathan Corbet , David Hildenbrand , dwmw@amazon.com, foersleo@amazon.de, Ian Rogers , jolsa@redhat.com, "Kirill A. Shutemov" , mark.rutland@arm.com, Mel Gorman , Minchan Kim , Ingo Molnar , namhyung@kernel.org, "Peter Zijlstra (Intel)" , Randy Dunlap , Rik van Riel , David Rientjes , Steven Rostedt , rppt@kernel.org, sblbir@amazon.com, shuah@kernel.org, sj38.park@gmail.com, snu@amazon.de, Vlastimil Babka , Vladimir Davydov , Yang Shi , Huang Ying , linux-damon@amazon.com, Linux MM , linux-doc@vger.kernel.org, LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: AF2C86D71 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 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? > + clear_page_idle(pte_page(*pte)); > + set_page_young(pte_page(*pte)); > + } > + *pte = pte_mkold(*pte); > + pte_unmap_unlock(pte, ptl); > + return; > + } > +