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=-23.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 8D6E2C4361B for ; Tue, 8 Dec 2020 07:42:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 34D1223A3C for ; Tue, 8 Dec 2020 07:42:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 34D1223A3C 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 B99486B005C; Tue, 8 Dec 2020 02:42:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B231A6B005D; Tue, 8 Dec 2020 02:42:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9EB1C6B0068; Tue, 8 Dec 2020 02:42:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0252.hostedemail.com [216.40.44.252]) by kanga.kvack.org (Postfix) with ESMTP id 88B4D6B005C for ; Tue, 8 Dec 2020 02:42:42 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4B7418249980 for ; Tue, 8 Dec 2020 07:42:42 +0000 (UTC) X-FDA: 77569322964.15.bite52_1412145273e5 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id 225D01814B0C7 for ; Tue, 8 Dec 2020 07:42:42 +0000 (UTC) X-HE-Tag: bite52_1412145273e5 X-Filterd-Recvd-Size: 9544 Received: from smtp-fw-9102.amazon.com (smtp-fw-9102.amazon.com [207.171.184.29]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Dec 2020 07:42:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1607413362; x=1638949362; h=from:to:cc:subject:date:message-id:in-reply-to: mime-version; bh=5nAvOheFRPFgUtfiqscEViDDQqJQXvSdA1jrKPlN6VQ=; b=cezMEXuJV/WmmujBFBKCheFRIUL5YP5KmqwRUEcHq4A+1R00SFgjffWt 35KPt92Uhv7AQ/QCawtIlAaXkOzEP/qxEIvgNUOls0cLAzf4PeSMk9mgI auPBePCoCmhzG1ovYqIwFooDAAz+W26+w5r/CjWfLKPT/+ydOwMVmftqz o=; X-IronPort-AV: E=Sophos;i="5.78,401,1599523200"; d="scan'208";a="102504134" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2c-87a10be6.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 08 Dec 2020 07:42:34 +0000 Received: from EX13D31EUA001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-2c-87a10be6.us-west-2.amazon.com (Postfix) with ESMTPS id A2109A1D31; Tue, 8 Dec 2020 07:42:31 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.161.43) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 8 Dec 2020 07:42:13 +0000 From: SeongJae Park To: SeongJae Park CC: Shakeel Butt , SeongJae Park , , 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 v22 01/18] mm: Introduce Data Access MONitor (DAMON) Date: Tue, 8 Dec 2020 08:41:59 +0100 Message-ID: <20201208074159.25172-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201126115157.6888-1-sjpark@amazon.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.161.43] X-ClientProxiedBy: EX13D13UWB002.ant.amazon.com (10.43.161.21) To EX13D31EUA001.ant.amazon.com (10.43.165.15) 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 Thu, 26 Nov 2020 12:51:57 +0100 SeongJae Park wrote: > Hi Shakeel, > > > Thanks for the review! :D > > On Wed, 25 Nov 2020 07:29:10 -0800 Shakeel Butt wrote: > > > On Tue, Oct 20, 2020 at 2:01 AM SeongJae Park wrote: > > > > > > From: SeongJae Park > > > > > > DAMON is a data access monitoring framework for the Linux kernel. The > > > core mechanisms of DAMON make it > > > > > > - accurate (the monitoring output is useful enough for DRAM level > > > performance-centric memory management; It might be inappropriate for > > > CPU Cache levels, though), > > > - light-weight (the monitoring overhead is normally low enough to be > > > applied online), and > > > - scalable (the upper-bound of the overhead is in constant range > > > regardless of the size of target workloads). > > > > > > Using this framework, hence, we can easily write efficient kernel space > > > data access monitoring applications. For example, the kernel's memory > > > management mechanisms can make advanced decisions using this. > > > Experimental data access aware optimization works that incurring high > > > access monitoring overhead could implemented again on top of this. > > > > > > Due to its simple and flexible interface, providing user space interface > > > would be also easy. Then, user space users who have some special > > > workloads can write personalized applications for better understanding > > > and optimizations of their workloads and systems. > > > > > > That said, this commit is implementing only basic data structures and > > > simple manipulation functions of the structures. The core mechanisms of > > > DAMON will be implemented by following commits. > > > > > > Signed-off-by: SeongJae Park > > > Reviewed-by: Leonard Foerster > > > Reviewed-by: Varad Gautam > > [...] > > I would suggest to separate > > the core (damon context) from the target related structs (target, > > region, addr range). > > To be honest, I unsure if I'm fully understanding what specific change you want > to make. So if I'm misunderstanding your point below, please let me know. > > Seems like you are concerning for future support of special kind use cases that > don't need targets/regions/addresses, such as page granularity monitoring that > having interest in only if the pages accessed or not, rather than access > frequency. In the context, your suggestion makes sense as the region > abstraction is only burden in the case, as I also mentioned in the cover > letter. This could be done via idle pages tracking, but DAMON will be able to > do this faster by reducing the number of user-kernel context switches. > > I once considered adding some change in the core part for efficient support of > such use cases, but resulted in believing that the best way for that is > implementing another primitive for the case and use it in a controlled way. > > In a high level, it should disable the 'adaptive regions adjustment' feature > and define it's own targets structs other than the damon_target. Then, your > implementation of the primitive callbacks should use your own targets. > > In more detail, the 'adaptive regions adjustment' can be disabled by setting > the min_nr_regions and max_nr_regions of the damon_ctx with same value, say, 0. > Your own targets structs could be stored in 'damon_callback->private'. Or, we > could add another 'private' field in damon_ctx for that. > > I think this will work, but I also admit that this could look like a hairy > hack to someone. Fundamentally, this is because the region based > overhead/accuracy handling is strongly coupled in the design. So, I think what > you are really suggesting is making DAMON more general by default and > supporting the region based overhead/accuracy handling additionally. > > If I'm understanding correctly, how about below like change? Obviously this > should be cleaned up a lot, but I just want to quickly share my idea and > discuss. Also note that it's based on the damon/next tree[1]. > > [1] https://github.com/sjp38/linux/tree/damon/next > > +enum damon_type { > + ARBITRARY_TARGETS, > + ADAPTIVE_REGIONS, > +}; > + > +struct damon_adaptive_regions_ctx { > + unsigned long min_nr_regions; > + unsigned long max_nr_regions; > + struct list_head targets; > + struct list_head schemes; > +}; > + > /** > * struct damon_ctx - Represents a context for each monitoring. This is the > * main interface that allows users to set the attributes and get the results > @@ -243,8 +255,6 @@ struct damon_ctx { > unsigned long sample_interval; > unsigned long aggr_interval; > unsigned long regions_update_interval; > - unsigned long min_nr_regions; > - unsigned long max_nr_regions; > > struct timespec64 last_aggregation; > struct timespec64 last_regions_update; > @@ -253,11 +263,14 @@ struct damon_ctx { > bool kdamond_stop; > struct mutex kdamond_lock; > > - struct list_head targets_list; /* 'damon_target' objects */ > - struct list_head schemes_list; /* 'damos' objects */ > - > struct damon_primitive primitive; > struct damon_callback callback; > + > + enum damon_type type; > + union { > + struct damon_adaptive_regions_ctx arctx; > + void *targets; > + }; > }; > > The patchset will first introduce DAMON as only ARBITRARY_TARGETS (or, would > TINY be a better name?) type supporting form. After that, following patch will > add ADAPTIVE_REGIONS type support. Do you think I'm correctly understanding > your point and above suggestion makes sense? In a private message, Shakeel confirmed I'm correnctly understanding his intention and asked next version. I will post next version soon. Thanks, SeongJae Park