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From: Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@redhat.com>
Cc: Glauber Costa <glommer@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Rik van Riel <riel@redhat.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH v3 4/6] KVM-GST: KVM Steal time registration
Date: Tue, 15 Feb 2011 16:48:47 +0100	[thread overview]
Message-ID: <1297784927.2413.28.camel@twins> (raw)
In-Reply-To: <4D5A9091.6090506@redhat.com>

On Tue, 2011-02-15 at 16:41 +0200, Avi Kivity wrote:
> > +static int kvm_register_steal_time(void)
> > +{
> > +     int cpu = smp_processor_id();
> > +     int low, high, ret;
> > +     struct kvm_steal_time *st =&per_cpu(steal_time, cpu);
> > +
> > +     if (!hypervisor_steal_time)
> > +             return 0;
> 
> You're using hypervisor_steal_time to communicate the existence of the 
> feature.  Yuck. 

Yeah, ideally we make steal_time_clock() a proper paravirt op with:

u64 native_steal_time_clock(int cpu)
{
	WARN_ONCE(1, "Using steal_time_clock() on actual hardware..\n");
	return 0;
}

And use paravirt_enabled() to avoid calling it where possible. Then once
we have all the jump_label stuff sorted we can make paravirt_enabled() a
static_branch() and it'll just go away on native.



  reply	other threads:[~2011-02-15 15:48 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-11 18:19 [PATCH v3 0/6] Steal time for KVM Glauber Costa
2011-02-11 18:19 ` [PATCH v3 1/6] KVM-HDR: KVM Steal time implementation Glauber Costa
2011-02-15 14:25   ` Avi Kivity
2011-02-11 18:19 ` [PATCH v3 2/6] KVM-HV: " Glauber Costa
2011-02-15 14:34   ` Avi Kivity
2011-02-11 18:19 ` [PATCH v3 3/6] KVM-GST: KVM Steal time accounting Glauber Costa
2011-02-11 19:05   ` Peter Zijlstra
2011-02-12 23:46     ` Glauber Costa
2011-02-15 14:35   ` Avi Kivity
2011-02-15 14:45     ` Peter Zijlstra
2011-02-15 15:17       ` Avi Kivity
2011-02-15 15:24         ` Rik van Riel
2011-02-15 15:26           ` Avi Kivity
2011-02-15 15:27         ` Peter Zijlstra
2011-02-11 18:19 ` [PATCH v3 4/6] KVM-GST: KVM Steal time registration Glauber Costa
2011-02-15 14:41   ` Avi Kivity
2011-02-15 15:48     ` Peter Zijlstra [this message]
2011-02-11 18:19 ` [PATCH v3 5/6] KVM-GST: adjust scheduler cpu power Glauber Costa
2011-02-11 19:05   ` Peter Zijlstra
2011-02-11 18:19 ` [PATCH v3 6/6] Describe KVM_MSR_STEAL_TIME Glauber Costa

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