Received: by 2002:ac0:a5a6:0:0:0:0:0 with SMTP id m35-v6csp385292imm; Thu, 13 Sep 2018 23:22:36 -0700 (PDT) X-Google-Smtp-Source: ANB0VdYfFcYiQbnZWD0K0d1hkK7qkRu5GCMfSqf3sVBKeiMrXfhXz2on8huzvI2O/8pVNaI5evI5 X-Received: by 2002:a63:7f06:: with SMTP id a6-v6mr10238899pgd.296.1536906156264; Thu, 13 Sep 2018 23:22:36 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1536906156; cv=none; d=google.com; s=arc-20160816; b=ldO9mcauOKxxG09Rr6EvW21NOGG8BsLQI9WclX4+wR1bh0EggJ3jCf20M8y+1JdazL UnoVPqAAda/yv3bP0XplEJmZ4OU4v/tpKdK/GDEmndYpjF5MmsOcf5PyrkR4TKY2H1/o PG+mBKm/ac7br1RBG4SeAFVUe1VFMpC8o5jPkO2byvpkR0DRmwFxy4VJEC5SKoNewp3K wvq0ewPIbdYzpiBPWfyC+sM0g19zjd9jFdIaUY+Bk6K39r8K60aJE23GJ1MpxcCsfs0o X51o4vHhK2dc0IRr6h+4CmwX4pMPhoY7A9vJ5XRhvfyMnIrHDeIw3ad0vCtbkZm11QUD qliA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=i5+Qr4OWxB1YTvWgMAvI8wxtbwVTG+2Qe36pRHubbgc=; b=cGg6J9UEIYPLzAiHpMzQVFOtPRRvc0smnfsRc1v3ECR3bw04omYF6L5vNZ8QT/BT6d PRX8pAJJ8fDd7xlJylenQQ8uAa6iHnapYyegNSgiQJ+EuVRspKJwtB+pvNhvFbo09TRP 6+0JsowNOd3HKfKBm4AKGVqvUHe2C/xts71YF0dnYqqF5ecET6XcIu9W42B9BrYF4LhJ nu58rM+H5Vzl/4/rMNb/4eSTwl+BWteOQjrMhkDlIKmu1134o7Gma3zaz3/gEsJp5lL7 m+BMpmY7na3sZiL1Seu70u5gZPW8JnuWiVeDeD4EAO+I5aQzyxle0phRRaK3KnHUDKqG pbmg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id n7-v6si6068878plp.71.2018.09.13.23.22.20; Thu, 13 Sep 2018 23:22:36 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727848AbeINLee (ORCPT + 99 others); Fri, 14 Sep 2018 07:34:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:41956 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726955AbeINLee (ORCPT ); Fri, 14 Sep 2018 07:34:34 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A6D6FAE4A; Fri, 14 Sep 2018 06:21:35 +0000 (UTC) Date: Fri, 14 Sep 2018 08:21:32 +0200 From: Michal Hocko To: Jann Horn Cc: Prakash Sangappa , Dave Hansen , Anshuman Khandual , Andrew Morton , kernel list , Linux-MM , Linux API , "Kirill A . Shutemov" , n-horiguchi@ah.jp.nec.com, drepper@gmail.com, rientjes@google.com, nao.horiguchi@gmail.com, steven.sistare@oracle.com Subject: Re: [RFC PATCH] Add /proc//numa_vamaps for numa node information Message-ID: <20180914062132.GI20287@dhcp22.suse.cz> References: <2ce01d91-5fba-b1b7-2956-c8cc1853536d@intel.com> <33f96879-351f-674a-ca23-43f233f4eb1d@linux.vnet.ibm.com> <82d2b35c-272a-ad02-692f-2c109aacdfb6@oracle.com> <8569dabb-4930-aa20-6249-72457e2df51e@intel.com> <51145ccb-fc0d-0281-9757-fb8a5112ec24@oracle.com>

<94ee0b6c-4663-0705-d4a8-c50342f6b483@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 14-09-18 03:33:28, Jann Horn wrote: > On Wed, Sep 12, 2018 at 10:43 PM prakash.sangappa > wrote: > > On 05/09/2018 04:31 PM, Dave Hansen wrote: > > > On 05/07/2018 06:16 PM, prakash.sangappa wrote: > > >> It will be /proc//numa_vamaps. Yes, the behavior will be > > >> different with respect to seeking. Output will still be text and > > >> the format will be same. > > >> > > >> I want to get feedback on this approach. > > > I think it would be really great if you can write down a list of the > > > things you actually want to accomplish. Dare I say: you need a > > > requirements list. > > > > > > The numa_vamaps approach continues down the path of an ever-growing list > > > of highly-specialized /proc/ files. I don't think that is > > > sustainable, even if it has been our trajectory for many years. > > > > > > Pagemap wasn't exactly a shining example of us getting new ABIs right, > > > but it sounds like something along those is what we need. > > > > Just sent out a V2 patch. This patch simplifies the file content. It > > only provides VA range to numa node id information. > > > > The requirement is basically observability for performance analysis. > > > > - Need to be able to determine VA range to numa node id information. > > Which also gives an idea of which range has memory allocated. > > > > - The proc file /proc//numa_vamaps is in text so it is easy to > > directly view. > > > > The V2 patch supports seeking to a particular process VA from where > > the application could read the VA to numa node id information. > > > > Also added the 'PTRACE_MODE_READ_REALCREDS' check when opening the > > file /proc file as was indicated by Michal Hacko > > procfs files should use PTRACE_MODE_*_FSCREDS, not PTRACE_MODE_*_REALCREDS. Out of my curiosity, what is the semantic difference? At least kernel_move_pages uses PTRACE_MODE_READ_REALCREDS. Is this a bug? -- Michal Hocko SUSE Labs