From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: question regarding intel_idle inside kvm Date: Mon, 19 Mar 2012 14:20:46 +0100 Message-ID: <4F6732AE.90205@free.fr> References: <4F626B05.9070909@free.fr> <4F67273E.2070204@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from smtp1-g21.free.fr ([212.27.42.1]:40433 "EHLO smtp1-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752528Ab2CSNU7 (ORCPT ); Mon, 19 Mar 2012 09:20:59 -0400 In-Reply-To: <4F67273E.2070204@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/19/2012 01:31 PM, Avi Kivity wrote: > On 03/16/2012 12:19 AM, Daniel Lezcano wrote: >> Hi all, >> >> I recently did some modification in the cpuidle core and the patches >> were merge to linux-next. >> Someone reported a problem with the intel_idle cpuidle driver. >> >> I tried to reproduce the problem with kvm but the kernel fails to >> intialize the driver because of intel_intel_init function fails in the >> processor probe. >> >> After digging a bit, I found it fails at: >> >> drivers/idle/intel_idle.c >> >> static int intel_idle_probe(void) >> { >> >> ... >> >> >> if (boot_cpu_data.cpuid_level< CPUID_MWAIT_LEAF) >> return -ENODEV; >> >> ^^^^^ >> >> ... >> >> } >> >> I assumed the virtualized processor does not support this, so I >> specified the "-cpu host" because the host was running the intel_idle >> driver. But the driver still fails in kvm. >> >> I was wondering why that happens ? Does anyone have an idea of this >> problem ? > intel_idle() uses mwait, which kvm does not virtualize (it's very > expensive to do so and brings no benefits). Ok, thanks for the information. I was afraid of that :/ I will go to for a real host then :) Thanks ! -- Daniel