From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 370097D2F0 for ; Wed, 7 Aug 2019 21:55:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388945AbfHGVzw (ORCPT ); Wed, 7 Aug 2019 17:55:52 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:40208 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388620AbfHGVzw (ORCPT ); Wed, 7 Aug 2019 17:55:52 -0400 Received: by mail-pg1-f195.google.com with SMTP id w10so42870980pgj.7 for ; Wed, 07 Aug 2019 14:55:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=fPDNifyL3Y36NBVemhHSXF79qGomK0S4tenrlniMG8c=; b=iLFial3WG2Y7hC5RmH/BPZMbk7K/mSRsub86lIBJhU4yCFb7muLzqQlM2Rw/ElKGgC SFjKYwdRoliyNAlbyClW8nV7pvHzWz0n8BGIO7Li2Qvwc3w0FvMgmdrCGjAVrSK9JbBy BL0fPr4WaEXa+YoPzJ+O512HUakd8rmUXyXUM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=fPDNifyL3Y36NBVemhHSXF79qGomK0S4tenrlniMG8c=; b=Xsxwfm24lUR4c3dpgceA5woMEDS9Ft/lFn4K1w4PESTEs7pR27knjVA6oaVGm1j0AP 0zWedRTglJa0PCNtFWqicI+PSNXe5LI1H0W6Aq+099tO7CAywVQWVb4ltDfaSgqUAMZc 2Q/4Rrew026WHDUBNtieaRX0RnOAwct5r5JhvWR1tiCZZbj017ORzJ8SCnKCaTa92Vwj Sc2Ev3BzBMZ4RMtmzaA19qO1n/Z67ZFFR3KPci3kl/Yx+FwlpcpNvJGaNy8FBJg6dDt1 Ugv5HecN/3NZN7oLOucMsrilSSwuGJLekQjVZmRVdV0snVGLDWLMjD8IL7JAlv1PqR57 Zdqg== X-Gm-Message-State: APjAAAURw5G5JtdBDms3IJKaXNDgJuvafBCOCLbjHa3ocbUixTnjAQzs Qi0uCinanznkOnImMNqBHEWg6w== X-Google-Smtp-Source: APXvYqxtYbX1J2T4gE/+OoiVyWtnb2A4+C1faUKsGzqUpJz/BeHl7Ul7v7RUi0zJvoSnKkCTeSkNNg== X-Received: by 2002:aa7:9afc:: with SMTP id y28mr11421501pfp.252.1565214951446; Wed, 07 Aug 2019 14:55:51 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id z4sm79672843pgp.80.2019.08.07.14.55.50 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 07 Aug 2019 14:55:50 -0700 (PDT) Date: Wed, 7 Aug 2019 17:55:49 -0400 From: Joel Fernandes To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Alexey Dobriyan , Borislav Petkov , Brendan Gregg , Catalin Marinas , Christian Hansen , dancol@google.com, fmayer@google.com, "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Kees Cook , kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Mike Rapoport , minchan@kernel.org, namhyung@google.com, paulmck@linux.ibm.com, Robin Murphy , Roman Gushchin , Stephen Rothwell , surenb@google.com, Thomas Gleixner , tkjos@google.com, Vladimir Davydov , Vlastimil Babka , Will Deacon Subject: Re: [PATCH v5 1/6] mm/page_idle: Add per-pid idle page tracking using virtual index Message-ID: <20190807215549.GB14622@google.com> References: <20190807171559.182301-1-joel@joelfernandes.org> <20190807130402.49c9ea8bf144d2f83bfeb353@linux-foundation.org> <20190807204530.GB90900@google.com> <20190807135840.92b852e980a9593fe91fbf59@linux-foundation.org> <20190807213105.GA14622@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190807213105.GA14622@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Aug 07, 2019 at 05:31:05PM -0400, Joel Fernandes wrote: > On Wed, Aug 07, 2019 at 01:58:40PM -0700, Andrew Morton wrote: > > On Wed, 7 Aug 2019 16:45:30 -0400 Joel Fernandes wrote: > > > > > On Wed, Aug 07, 2019 at 01:04:02PM -0700, Andrew Morton wrote: > > > > On Wed, 7 Aug 2019 13:15:54 -0400 "Joel Fernandes (Google)" wrote: > > > > > > > > > In Android, we are using this for the heap profiler (heapprofd) which > > > > > profiles and pin points code paths which allocates and leaves memory > > > > > idle for long periods of time. This method solves the security issue > > > > > with userspace learning the PFN, and while at it is also shown to yield > > > > > better results than the pagemap lookup, the theory being that the window > > > > > where the address space can change is reduced by eliminating the > > > > > intermediate pagemap look up stage. In virtual address indexing, the > > > > > process's mmap_sem is held for the duration of the access. > > > > > > > > So is heapprofd a developer-only thing? Is heapprofd included in > > > > end-user android loads? If not then, again, wouldn't it be better to > > > > make the feature Kconfigurable so that Android developers can enable it > > > > during development then disable it for production kernels? > > > > > > Almost all of this code is already configurable with > > > CONFIG_IDLE_PAGE_TRACKING. If you disable it, then all of this code gets > > > disabled. > > > > > > Or are you referring to something else that needs to be made configurable? > > > > Yes - the 300+ lines of code which this patchset adds! > > > > The impacted people will be those who use the existing > > idle-page-tracking feature but who will not use the new feature. I > > guess we can assume this set is small... > > Yes, I think this set should be small. The code size increase of page_idle.o > is from ~1KB to ~2KB. Most of the extra space is consumed by > page_idle_proc_generic() function which this patch adds. I don't think adding > another CONFIG option to disable this while keeping existing > CONFIG_IDLE_PAGE_TRACKING enabled, is worthwhile but I am open to the > addition of such an option if anyone feels strongly about it. I believe that > once this patch is merged, most like this new interface being added is what s/most like/most likely/ > will be used more than the old interface (for some of the usecases) so it > makes sense to keep it alive with CONFIG_IDLE_PAGE_TRACKING. > > thanks, > > - Joel >