Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757456Ab0FPIHS (ORCPT ); Wed, 16 Jun 2010 04:07:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45700 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753055Ab0FPIHP (ORCPT ); Wed, 16 Jun 2010 04:07:15 -0400 Message-ID: <4C18877E.9070605@redhat.com> Date: Wed, 16 Jun 2010 16:12:46 +0800 From: Jason Wang User-Agent: Thunderbird 2.0.0.22 (X11/20090609) MIME-Version: 1.0 To: Zachary Amsden CC: Avi Kivity , mtosatti@redhat.com, glommer@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, john stultz , Thomas Gleixner Subject: Re: [PATCH 12/17] Add helper function get_kernel_ns References: <1276587259-32319-1-git-send-email-zamsden@redhat.com> <1276587259-32319-13-git-send-email-zamsden@redhat.com> <4C173CC3.8000506@redhat.com> <4C17EAA5.90009@redhat.com> In-Reply-To: <4C17EAA5.90009@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2164 Lines: 67 Zachary Amsden wrote: > On 06/14/2010 10:41 PM, Avi Kivity wrote: > >> On 06/15/2010 10:34 AM, Zachary Amsden wrote: >> >>> Add a helper function for the multiple places this is used. Note >>> that it >>> must not be called in preemptible context, as that would mean the kernel >>> could enter software suspend state, which would cause non-atomic >>> operation >>> of the monotonic_to_bootbased computation. >>> >>> Open question: should the KVM_SET_CLOCK / KVM_GET_CLOCK ioctls use this >>> as well? Currently, they are not bootbased (but perhaps should be). >>> >>> Signed-off-by: Zachary Amsden >>> --- >>> arch/x86/kvm/x86.c | 26 +++++++++++++------------- >>> 1 files changed, 13 insertions(+), 13 deletions(-) >>> >>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>> index 703ea43..15c7317 100644 >>> --- a/arch/x86/kvm/x86.c >>> +++ b/arch/x86/kvm/x86.c >>> @@ -915,6 +915,16 @@ static void kvm_get_time_scale(uint32_t >>> scaled_khz, uint32_t base_khz, >>> __func__, base_khz, scaled_khz, shift, *pmultiplier); >>> } >>> >>> +static inline u64 get_kernel_ns(void) >>> +{ >>> + struct timespec ts; >>> + >>> + WARN_ON(preemptible()); >>> + ktime_get_ts(&ts); >>> + monotonic_to_bootbased(&ts); >>> + return timespec_to_ns(&ts); >>> +} >>> + >>> static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); >>> >>> >> Isn't something like this a candidate for the time infrastructure? >> >> > > Should it be? It certainly seems reasonable. > > > Also, should we be using it for the cases KVM_GET_CLOCK / > KVM_SET_CLOCK? It seems global kvmclock_offset for the VM ignores the > bootbased conversion. > > Yes we should. > Zach > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/