From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [patch 05/24] Xen-paravirt_ops: Add pagetable accessors to pack and unpack pagetable entries Date: Thu, 22 Feb 2007 10:20:02 +1100 Message-ID: <1172100002.13378.42.camel@localhost.localdomain> References: <20070221205254.169835700@goop.org> <20070221205322.869165491@goop.org> <200702212315.12883.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200702212315.12883.ak@suse.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Andi Kleen Cc: Chris Wright , virtualization@lists.osdl.org, Andrew Morton , xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org On Wed, 2007-02-21 at 23:15 +0100, Andi Kleen wrote: > On Wednesday 21 February 2007 21:52, Jeremy Fitzhardinge wrote: > > Add a set of accessors to pack, unpack and modify page table entries > > (at all levels). This allows a paravirt implementation to control the > > contents of pgd/pmd/pte entries. For example, Xen uses this to > > convert the (pseudo-)physical address into a machine address when > > populating a pagetable entry, and converting back to pphys address > > when an entry is read. > > Do you have some lmbench numbers before/after this change? > iirc at least fork and exit do a lot of pte accesses in various forms. > If it's measurable it might be needed to patch those for the native case. Yes, __mkpte must be patched to avoid performance embarrassment. Jeremy, did you want me to do this, or are you happy to? Rusty. PS. I really must revise my "paravirt-ops counter" patch which tallies how much each op is getting called.