From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: Re: [patch 05/24] Xen-paravirt_ops: Add pagetable accessors to pack and unpack pagetable entries Date: Wed, 21 Feb 2007 15:27:21 -0800 Message-ID: <45DCD559.1040301@goop.org> References: <20070221205254.169835700@goop.org> <20070221205322.869165491@goop.org> <200702212315.12883.ak@suse.de> <1172100002.13378.42.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1172100002.13378.42.camel@localhost.localdomain> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Rusty Russell Cc: xen-devel@lists.xensource.com, Andi Kleen , linux-kernel@vger.kernel.org, Chris Wright , virtualization@lists.osdl.org, Andrew Morton List-Id: virtualization@lists.linuxfoundation.org Rusty Russell wrote: > 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? > I'm working on it now. I'll mail out a proposal in a little bit. J