From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754349AbaHAPwO (ORCPT ); Fri, 1 Aug 2014 11:52:14 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:40277 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750851AbaHAPwN (ORCPT ); Fri, 1 Aug 2014 11:52:13 -0400 Date: Fri, 1 Aug 2014 08:52:08 -0700 From: Matt Wilson To: David Vrabel Cc: Matt Rushton , konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, msw@amazon.com, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, Matt Rushton Subject: Re: [PATCH v2 2/2] xen/setup: Remap Xen Identity Mapped RAM Message-ID: <20140801155206.GA13865@u109add4315675089e695.ant.amazon.com> References: <1405814495-10868-1-git-send-email-mrushton@amazon.com> <1405814495-10868-2-git-send-email-mrushton@amazon.com> <53DA805D.4020300@citrix.com> <53DBA9AC.8000302@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53DBA9AC.8000302@citrix.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 01, 2014 at 03:52:28PM +0100, David Vrabel wrote: > On 31/07/14 18:43, David Vrabel wrote: > > On 20/07/14 01:01, Matt Rushton wrote: > >> Instead of ballooning up and down dom0 memory this remaps the existing mfns > >> that were replaced by the identity map. The reason for this is that the > >> existing implementation ballooned memory up and and down which caused dom0 > >> to have discontiguous pages. In some cases this resulted in the use of bounce > >> buffers which reduced network I/O performance significantly. This change will > >> honor the existing order of the pages with the exception of some boundary > >> conditions. > >> > >> To do this we need to update both the Linux p2m table and the Xen m2p table. > >> Particular care must be taken when updating the p2m table since it's important > >> to limit table memory consumption and reuse the existing leaf pages which get > >> freed when an entire leaf page is set to the identity map. To implement this, > >> mapping updates are grouped into blocks with table entries getting cached > >> temporarily and then released. > >> > >> On my test system before: > >> Total pages: 2105014 > >> Total contiguous: 1640635 > >> > >> After: > >> Total pages: 2105014 > >> Total contiguous: 2098904 > > > > Applied to devel/for-linus-3.17 > > Unfortunately, this produces too many WARNINGs on some boxes or > with certain configurations. Hi David, Do you have more information about the systems or configurations that showed a problem? --msw