From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Piggin Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Date: Mon, 12 Sep 2016 13:35:36 +1000 Message-ID: <20160912133536.1bdb57a9@roar.ozlabs.ibm.com> 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: 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 , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Xiao Guangrong , Arnd Bergmann , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Dave Hansen , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton , "Kirill A. Shutemov" List-Id: linux-api@vger.kernel.org On Sun, 11 Sep 2016 10:31:35 -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. Can you cc linux-arch when adding new syscalls (or other such things that need arch enablement). I wonder if the changelog for a new syscall should have a bit more grandeur. Without seeing patch 2, you might not know this was a new syscall just by reading the subject and changelog. mincore() defines other bits to be reserved, but I guess it probably breaks things if you suddenly started using them. It's a bit sad to introduce a new syscall for this and immediately use up all bits that can be returned. Would it be a serious problem to return a larger mask per page? Thanks, Nick From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f194.google.com ([209.85.192.194]:34350 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756080AbcILDfq (ORCPT ); Sun, 11 Sep 2016 23:35:46 -0400 Date: Mon, 12 Sep 2016 13:35:36 +1000 From: Nicholas Piggin Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160912133536.1bdb57a9@roar.ozlabs.ibm.com> In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> 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 Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dan Williams Cc: linux-mm@kvack.org, Andrea Arcangeli , Xiao Guangrong , Arnd Bergmann , linux-nvdimm@lists.01.org, linux-api@vger.kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, Andrew Morton , "Kirill A. Shutemov" , linux-arch@vger.kernel.org Message-ID: <20160912033536.6e2cQTRViylX5fxwQ6bi8-laKsIlNaZIffKjASD9CzA@z> On Sun, 11 Sep 2016 10:31:35 -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. Can you cc linux-arch when adding new syscalls (or other such things that need arch enablement). I wonder if the changelog for a new syscall should have a bit more grandeur. Without seeing patch 2, you might not know this was a new syscall just by reading the subject and changelog. mincore() defines other bits to be reserved, but I guess it probably breaks things if you suddenly started using them. It's a bit sad to introduce a new syscall for this and immediately use up all bits that can be returned. Would it be a serious problem to return a larger mask per page? Thanks, Nick From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x244.google.com (mail-pf0-x244.google.com [IPv6:2607:f8b0:400e:c00::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 7C6EC1A1DF1 for ; Sun, 11 Sep 2016 20:35:46 -0700 (PDT) Received: by mail-pf0-x244.google.com with SMTP id i75so2494218pfa.2 for ; Sun, 11 Sep 2016 20:35:46 -0700 (PDT) Date: Mon, 12 Sep 2016 13:35:36 +1000 From: Nicholas Piggin Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160912133536.1bdb57a9@roar.ozlabs.ibm.com> In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> References: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Andrea Arcangeli , linux-arch@vger.kernel.org, Xiao Guangrong , Arnd Bergmann , linux-nvdimm@lists.01.org, linux-api@vger.kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , "Kirill A. Shutemov" List-ID: On Sun, 11 Sep 2016 10:31:35 -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. Can you cc linux-arch when adding new syscalls (or other such things that need arch enablement). I wonder if the changelog for a new syscall should have a bit more grandeur. Without seeing patch 2, you might not know this was a new syscall just by reading the subject and changelog. mincore() defines other bits to be reserved, but I guess it probably breaks things if you suddenly started using them. It's a bit sad to introduce a new syscall for this and immediately use up all bits that can be returned. Would it be a serious problem to return a larger mask per page? Thanks, Nick _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f69.google.com (mail-pa0-f69.google.com [209.85.220.69]) by kanga.kvack.org (Postfix) with ESMTP id 94AD26B0038 for ; Sun, 11 Sep 2016 23:35:51 -0400 (EDT) Received: by mail-pa0-f69.google.com with SMTP id fu12so42949918pac.1 for ; Sun, 11 Sep 2016 20:35:51 -0700 (PDT) Received: from mail-pf0-x241.google.com (mail-pf0-x241.google.com. [2607:f8b0:400e:c00::241]) by mx.google.com with ESMTPS id h2si13550880pah.243.2016.09.11.20.35.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 11 Sep 2016 20:35:50 -0700 (PDT) Received: by mail-pf0-x241.google.com with SMTP id x24so7416735pfa.3 for ; Sun, 11 Sep 2016 20:35:46 -0700 (PDT) Date: Mon, 12 Sep 2016 13:35:36 +1000 From: Nicholas Piggin Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160912133536.1bdb57a9@roar.ozlabs.ibm.com> In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> 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 Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: linux-mm@kvack.org, Andrea Arcangeli , Xiao Guangrong , Arnd Bergmann , linux-nvdimm@lists.01.org, linux-api@vger.kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, Andrew Morton , "Kirill A. Shutemov" , linux-arch@vger.kernel.org On Sun, 11 Sep 2016 10:31:35 -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. Can you cc linux-arch when adding new syscalls (or other such things that need arch enablement). I wonder if the changelog for a new syscall should have a bit more grandeur. Without seeing patch 2, you might not know this was a new syscall just by reading the subject and changelog. mincore() defines other bits to be reserved, but I guess it probably breaks things if you suddenly started using them. It's a bit sad to introduce a new syscall for this and immediately use up all bits that can be returned. Would it be a serious problem to return a larger mask per page? Thanks, Nick -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756645AbcILDft (ORCPT ); Sun, 11 Sep 2016 23:35:49 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:34350 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756080AbcILDfq (ORCPT ); Sun, 11 Sep 2016 23:35:46 -0400 Date: Mon, 12 Sep 2016 13:35:36 +1000 From: Nicholas Piggin 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" , linux-arch@vger.kernel.org Subject: Re: [RFC PATCH 1/2] mm, mincore2(): retrieve dax and tlb-size attributes of an address range Message-ID: <20160912133536.1bdb57a9@roar.ozlabs.ibm.com> In-Reply-To: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> References: <147361509579.17004.5258725187329709824.stgit@dwillia2-desk3.amr.corp.intel.com> Organization: IBM X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 11 Sep 2016 10:31:35 -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. Can you cc linux-arch when adding new syscalls (or other such things that need arch enablement). I wonder if the changelog for a new syscall should have a bit more grandeur. Without seeing patch 2, you might not know this was a new syscall just by reading the subject and changelog. mincore() defines other bits to be reserved, but I guess it probably breaks things if you suddenly started using them. It's a bit sad to introduce a new syscall for this and immediately use up all bits that can be returned. Would it be a serious problem to return a larger mask per page? Thanks, Nick