From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Resend: patch: qemu + hugetlbfs.. Date: Tue, 26 Aug 2008 11:11:50 +0300 Message-ID: <48B3BAC6.90903@qumranet.com> References: <4873E400.4000409@third-harmonic.com> <4873F395.6030209@codemonkey.ws> <4874051A.8000802@third-harmonic.com> <48740F86.3050306@codemonkey.ws> <20080709170301.GA11439@dmt.cnet> <4874F156.2010708@codemonkey.ws> <48763B86.6060402@third-harmonic.com> <48764DAF.6060502@codemonkey.ws> <48766E03.4090901@third-harmonic.com> <48767558.50301@codemonkey.ws> <48767B20.20806@third-harmonic.com> <4876815E.3010109@codemonkey.ws> <48B33AAD.8000508@third-harmonic.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Anthony Liguori , Marcelo Tosatti , john.cooper@redhat.com To: john cooper Return-path: Received: from il.qumranet.com ([212.179.150.194]:53516 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751936AbYHZILw (ORCPT ); Tue, 26 Aug 2008 04:11:52 -0400 In-Reply-To: <48B33AAD.8000508@third-harmonic.com> Sender: kvm-owner@vger.kernel.org List-ID: john cooper wrote: > This patch from over a month ago doesn't seem to have > made it into kvm-73 and may have been lost in the > shuffle. Attached is essentially the same patch but > as applied to kvm-73, and validated relative to that > version. > I must have missed it. Thanks for persisting. > In a nutshell the intention here is to allow > preallocation of guest huge page backed memory at > qemu initialization time to avoid a quirk in the > kernel's huge page accounting allowing overcommit > of huge pages. Failure of the kernel to resolve a > guest fault to overcommitted huge page memory during > runtime results in sigkill termination of the guest. > This patch provides the option of avoiding such > behavior at the cost of up-front preallocation of > physical huge pages backing the guest. > What is the motivation for providing an option to disable this? If we can detect mem-path is backed by huge pages somehow, I think we can prefault the memory unconditionally. -- error compiling committee.c: too many arguments to function