From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gianluca Guida Subject: [PATCH 0/4] Out-of-sync L1 shadows. Date: Fri, 20 Jun 2008 18:31:36 +0100 Message-ID: <485BE978.5020805@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hello, This set of patches let the guest write directly to L1 pagetables, thus making them temporarily out of sync (OOS) with their shadows. L2 and higher level page tables are still always emulated. This let us avoids most of the pagetable write emulations, resulting in a generic speedup, especially in Windows guests. The policy implemented in the fourth patch (that put OOS a pagetable whenever the guest tries to write to it), has proven to be a win for guest with up to 4 vcpus. Patches: - oos-base.patch: implement the basic mechanisms to unsync and resync pages at appropriate times; - oos-optimize-1.oos_fixups.patch: OOS writable mappings reverse map to avoid shadow brute-force search on resyncs; - oos-optimize-2.snapshots.patch: add snapshots of guest pages to allow faster revalidation of OOS pages on resync; - oos-policy.always.patch: always unsync pages on guest writes; Benchmarks results: Results for a Windows Server 2003 DDK Build (build -cPzM 3) with warm cache (third run) on a Core2 6420 @ 2.13GhZ. current OOS Diff 32bit 1vcpu 05:27.00 04:38.00 -14.98% PAE 1vcpu 06:49.00 05:05.00 -25.43% 64bit 1vcpu 06:56.00 05:35.00 -19.47% 32bit 2vcpu 03:31.00 03:06.00 -11.85% PAE 2vcpu 04:07.00 03:17.00 -20.24% 64bit 2vcpu 04:05.00 03:47.00 -7.35% Thanks, Gianluca