From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bk0-f42.google.com (mail-bk0-f42.google.com [209.85.214.42]) by kanga.kvack.org (Postfix) with ESMTP id E92C86B0036 for ; Tue, 8 Apr 2014 16:51:31 -0400 (EDT) Received: by mail-bk0-f42.google.com with SMTP id mx12so1308392bkb.1 for ; Tue, 08 Apr 2014 13:51:31 -0700 (PDT) Received: from mail-bk0-f50.google.com (mail-bk0-f50.google.com [209.85.214.50]) by mx.google.com with ESMTPS id nr10si1684866bkb.71.2014.04.08.13.51.29 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Apr 2014 13:51:30 -0700 (PDT) Received: by mail-bk0-f50.google.com with SMTP id w10so1266202bkz.23 for ; Tue, 08 Apr 2014 13:51:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1396883443-11696-1-git-send-email-mgorman@suse.de> <1396883443-11696-3-git-send-email-mgorman@suse.de> <5342C517.2020305@citrix.com> <20140407154935.GD7292@suse.de> <20140407161910.GJ1444@moon> <20140407182854.GH7292@suse.de> <5342FC0E.9080701@zytor.com> <20140407193646.GC23983@moon> <5342FFB0.6010501@zytor.com> <20140407212535.GJ7292@suse.de> Date: Tue, 8 Apr 2014 13:51:28 -0700 Message-ID: Subject: Re: [PATCH 2/3] x86: Define _PAGE_NUMA with unused physical address bits PMD and PTE levels From: Steven Noonan Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: "H. Peter Anvin" Cc: Mel Gorman , Cyrill Gorcunov , David Vrabel , Linus Torvalds , Ingo Molnar , Rik van Riel , Andrew Morton , Peter Zijlstra , Andrea Arcangeli , Linux-MM , Linux-X86 , LKML , Pavel Emelyanov On Tue, Apr 8, 2014 at 8:16 AM, H. Peter Anvin wrote: > > > Of course, it would also be preferable if Amazon (or anything else) didn't need Xen PV :( Well Amazon doesn't expose NUMA on PV, only on HVM guests. > On April 7, 2014 9:04:53 PM PDT, Steven Noonan wrote: >>On Mon, Apr 7, 2014 at 2:25 PM, Mel Gorman wrote: >>> On Mon, Apr 07, 2014 at 12:42:40PM -0700, H. Peter Anvin wrote: >>>> On 04/07/2014 12:36 PM, Cyrill Gorcunov wrote: >>>> > On Mon, Apr 07, 2014 at 12:27:10PM -0700, H. Peter Anvin wrote: >>>> >> On 04/07/2014 11:28 AM, Mel Gorman wrote: >>>> >>> >>>> >>> I had considered the soft-dirty tracking usage of the same bit. >>I thought I'd >>>> >>> be able to swizzle around it or a further worst case of having >>soft-dirty and >>>> >>> automatic NUMA balancing mutually exclusive. Unfortunately upon >>examination >>>> >>> it's not obvious how to have both of them share a bit and I >>suspect any >>>> >>> attempt to will break CRIU. In my current tree, NUMA_BALANCING >>cannot be >>>> >>> set if MEM_SOFT_DIRTY which is not particularly satisfactory. >>Next on the >>>> >>> list is examining if _PAGE_BIT_IOMAP can be used. >>>> >> >>>> >> Didn't we smoke the last user of _PAGE_BIT_IOMAP? >>>> > >>>> > Seems so, at least for non-kernel pages (not considering this bit >>references in >>>> > xen code, which i simply don't know but i guess it's used for >>kernel pages only). >>>> > >>>> >>>> David Vrabel has a patchset which I presumed would be pulled through >>the >>>> Xen tree this merge window: >>>> >>>> [PATCHv5 0/8] x86/xen: fixes for mapping high MMIO regions (and >>remove >>>> _PAGE_IOMAP) >>>> >>>> That frees up this bit. >>>> >>> >>> Thanks, I was not aware of that patch. Based on it, I intend to >>force >>> automatic NUMA balancing to depend on !XEN and see what the reaction >>is. If >>> support for Xen is really required then it potentially be re-enabled >>if/when >>> that series is merged assuming they do not need the bit for something >>else. >>> >> >>Amazon EC2 does have large memory instance types with NUMA exposed to >>the guest (e.g. c3.8xlarge, i2.8xlarge, etc), so it'd be preferable >>(to me anyway) if we didn't require !XEN. > > -- > Sent from my mobile phone. Please pardon brevity and lack of formatting. > > -- > 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 -- 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