From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: Partial huge page backing with KVM/qemu Date: Sun, 25 Aug 2013 11:52:10 +0300 Message-ID: <20130825085210.GI8218@redhat.com> References: <7F858974825DC945874D45551C161B941156CCC4@eusaamb105.ericsson.se> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "kvm@vger.kernel.org" To: Chris Leduc Return-path: Received: from mx1.redhat.com ([209.132.183.28]:13341 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756129Ab3HYIwO convert rfc822-to-8bit (ORCPT ); Sun, 25 Aug 2013 04:52:14 -0400 Content-Disposition: inline In-Reply-To: <7F858974825DC945874D45551C161B941156CCC4@eusaamb105.ericsson.se> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Aug 24, 2013 at 12:32:07AM +0000, Chris Leduc wrote: > Hi - In a KVM/qemu environment is it possible for the host to back on= ly a portion of the guests memory with huge pages?=9A In some situation= s it may not be desirable to back the entirety of a guest's memory with= huge pages (as can be done via libvirt memoryBacking option). What are those situations? > What would be very useful is to request huge pages in the guest, eith= er at boot time or dynamically, and have the host back them with physic= al huge pages, but not back the rest of the normal page guest memory wi= th huge pages from the host. >=20 > The equivalent in Xen is setting allowsuperpage=3D1 on the hypervisor= boot line. >=20 As far as I can tell this disables/enables use of huge pages by XEN vm, not something you say you want. =20 -- Gleb.