From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f179.google.com (mail-lb0-f179.google.com [209.85.217.179]) by kanga.kvack.org (Postfix) with ESMTP id 1AB0F6B0037 for ; Mon, 23 Jun 2014 16:07:00 -0400 (EDT) Received: by mail-lb0-f179.google.com with SMTP id z11so5208071lbi.38 for ; Mon, 23 Jun 2014 13:06:59 -0700 (PDT) Received: from mail-lb0-f181.google.com (mail-lb0-f181.google.com [209.85.217.181]) by mx.google.com with ESMTPS id nc2si35730842lbc.35.2014.06.23.13.06.57 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 23 Jun 2014 13:06:58 -0700 (PDT) Received: by mail-lb0-f181.google.com with SMTP id p9so5144516lbv.26 for ; Mon, 23 Jun 2014 13:06:57 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <53A88806.1060908@intel.com> 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> <53A88806.1060908@intel.com> From: Andy Lutomirski Date: Mon, 23 Jun 2014 13:06:37 -0700 Message-ID: Subject: Re: [PATCH v6 02/10] x86, mpx: add MPX specific mmap interface Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Qiaowei Ren , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , X86 ML , "linux-kernel@vger.kernel.org" , Linux MM On Mon, Jun 23, 2014 at 1:03 PM, Dave Hansen wrote: > 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. > Can the new vm_operation "name" be use for this? The magic "always written to core dumps" feature might need to be reconsidered. There's also arch_vma_name, but I just finished removing for x86, and I'd be a little sad to see it come right back. --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org