From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [RFC 5/7] kvm steal time implementation Date: Thu, 26 Aug 2010 18:13:07 -0400 Message-ID: <4C76E6F3.5020402@redhat.com> References: <1282772597-4183-1-git-send-email-glommer@redhat.com> <1282772597-4183-2-git-send-email-glommer@redhat.com> <1282772597-4183-3-git-send-email-glommer@redhat.com> <1282772597-4183-4-git-send-email-glommer@redhat.com> <1282772597-4183-5-git-send-email-glommer@redhat.com> <1282772597-4183-6-git-send-email-glommer@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, avi@redhat.com, zamsden@redhat.com, mtosatti@redhat.com To: Glauber Costa Return-path: Received: from mx1.redhat.com ([209.132.183.28]:3005 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753127Ab0HZWNK (ORCPT ); Thu, 26 Aug 2010 18:13:10 -0400 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7QMD9at004286 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 26 Aug 2010 18:13:10 -0400 In-Reply-To: <1282772597-4183-6-git-send-email-glommer@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/25/2010 05:43 PM, Glauber Costa wrote: > This is the proposed kvm-side steal time implementation. > It is migration safe, as it checks flags at every read. > > Signed-off-by: Glauber Costa > --- > arch/x86/kernel/kvmclock.c | 35 +++++++++++++++++++++++++++++++++++ > 1 files changed, 35 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c > index eb9b76c..a1f4852 100644 > --- a/arch/x86/kernel/kvmclock.c > +++ b/arch/x86/kernel/kvmclock.c > @@ -18,6 +18,8 @@ > > #include > #include > +#include > +#include > #include > #include > #include > @@ -41,6 +43,7 @@ early_param("no-kvmclock", parse_no_kvmclock); > > /* The hypervisor will put information about time periodically here */ > static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); > +static DEFINE_PER_CPU(u64, steal_info); > static struct pvclock_wall_clock wall_clock; > > /* > @@ -82,6 +85,32 @@ static cycle_t kvm_clock_read(void) > return ret; > } > > +static DEFINE_PER_CPU(u64, steal_info); > + > +cputime_t kvm_get_steal_time(void) > +{ > + u64 delta = 0; > + u64 *last_steal_info, this_steal_info; > + struct pvclock_vcpu_time_info *src; > + > + src =&get_cpu_var(hv_clock); > + if (!(src->flags& PVCLOCK_STEAL_BIT)) > + goto out; > + > + this_steal_info = src->steal_time; > + put_cpu_var(hv_clock); > + > + last_steal_info =&get_cpu_var(steal_info); > + > + delta = this_steal_info - *last_steal_info; > + > + *last_steal_info = this_steal_info; > + put_cpu_var(steal_info); > + > +out: > + return msecs_to_cputime(delta); > +} Can this be changed to properly deal with overflow in src->steal_time, the same way we deal with (eg jiffie) overflow elsewhere in the kernel? -- All rights reversed