From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Date: Mon, 12 Sep 2016 23:44:05 -0700 Message-ID: <20160913064405.GA21069@infradead.org> References: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <147361509579.17004.5258725187329709824.stgit-p8uTFz9XbKj2zm6wflaqv1nYeNYlB/vhral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Andrea Arcangeli , Xiao Guangrong , Arnd Bergmann , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Dave Hansen , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org, Andrew Morton , "Kirill A. Shutemov" List-Id: linux-nvdimm@lists.01.org On Sun, Sep 11, 2016 at 10:31:35AM -0700, Dan Williams wrote: > As evidenced by this bug report [1], userspace libraries are interested > in whether a mapping is DAX mapped, i.e. no intervening page cache. > Rather than using the ambiguous VM_MIXEDMAP flag in smaps, provide an > explicit "is dax" indication as a new flag in the page vector populated > by mincore. And how exactly does an implementation detail like DAX matter for an application? The only thing that might matter is the atomicy boundary, but mincore is not the right interface for that. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753356AbcIMGoJ (ORCPT ); Tue, 13 Sep 2016 02:44:09 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:50664 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751389AbcIMGoI (ORCPT ); Tue, 13 Sep 2016 02:44:08 -0400 Date: Mon, 12 Sep 2016 23:44:05 -0700 From: Christoph Hellwig To: Dan Williams Cc: linux-mm@kvack.org, Andrea Arcangeli , Xiao Guangrong , Arnd Bergmann , linux-nvdimm@ml01.01.org, linux-api@vger.kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, Andrew Morton , "Kirill A. Shutemov" Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160913064405.GA21069@infradead.org> References: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: Mutt/1.6.1 (2016-04-27) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 11, 2016 at 10:31:35AM -0700, Dan Williams wrote: > As evidenced by this bug report [1], userspace libraries are interested > in whether a mapping is DAX mapped, i.e. no intervening page cache. > Rather than using the ambiguous VM_MIXEDMAP flag in smaps, provide an > explicit "is dax" indication as a new flag in the page vector populated > by mincore. And how exactly does an implementation detail like DAX matter for an application? The only thing that might matter is the atomicy boundary, but mincore is not the right interface for that. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id 22CFB6B0069 for ; Tue, 13 Sep 2016 02:44:09 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id ag5so392821560pad.2 for ; Mon, 12 Sep 2016 23:44:09 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id tq7si25988783pab.0.2016.09.12.23.44.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Sep 2016 23:44:06 -0700 (PDT) Date: Mon, 12 Sep 2016 23:44:05 -0700 From: Christoph Hellwig Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160913064405.GA21069@infradead.org> References: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: linux-mm@kvack.org, Andrea Arcangeli , Xiao Guangrong , Arnd Bergmann , linux-nvdimm@ml01.01.org, linux-api@vger.kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, Andrew Morton , "Kirill A. Shutemov" On Sun, Sep 11, 2016 at 10:31:35AM -0700, Dan Williams wrote: > As evidenced by this bug report [1], userspace libraries are interested > in whether a mapping is DAX mapped, i.e. no intervening page cache. > Rather than using the ambiguous VM_MIXEDMAP flag in smaps, provide an > explicit "is dax" indication as a new flag in the page vector populated > by mincore. And how exactly does an implementation detail like DAX matter for an application? The only thing that might matter is the atomicy boundary, but mincore is not the right interface for that. -- 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