Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756783AbaFWUDi (ORCPT ); Mon, 23 Jun 2014 16:03:38 -0400 Received: from mga09.intel.com ([134.134.136.24]:60923 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753073AbaFWUDh (ORCPT ); Mon, 23 Jun 2014 16:03:37 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,532,1400050800"; d="scan'208";a="562067770" Message-ID: <53A88806.1060908@intel.com> Date: Mon, 23 Jun 2014 13:03:18 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Andy Lutomirski , Qiaowei Ren , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar CC: x86@kernel.org, linux-kernel@vger.kernel.org, Linux MM Subject: Re: [PATCH v6 02/10] x86, mpx: add MPX specific mmap interface References: <1403084656-27284-1-git-send-email-qiaowei.ren@intel.com> <1403084656-27284-3-git-send-email-qiaowei.ren@intel.com> <53A884B2.5070702@mit.edu> In-Reply-To: <53A884B2.5070702@mit.edu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2014 12:49 PM, Andy Lutomirski wrote: > On 06/18/2014 02:44 AM, Qiaowei Ren wrote: >> This patch adds one MPX specific mmap interface, which only handles >> mpx related maps, including bounds table and bounds directory. >> >> In order to track MPX specific memory usage, this interface is added >> to stick new vm_flag VM_MPX in the vma_area_struct when create a >> bounds table or bounds directory. > > I imagine the linux-mm people would want to think about any new vm flag. > Why is this needed? These tables can take huge amounts of memory. In the worst-case scenario, the tables can be 4x the size of the data structure being tracked. IOW, a 1-page structure can require 4 bounds-table pages. My expectation is that folks using MPX are going to be keen on figuring out how much memory is being dedicated to it. With this feature, plus some grepping in /proc/$pid/smaps one could take a pretty good stab at it. I know VM flags are scarce, and I'm open to other ways to skin this cat. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/