linux-kernel - Re: [PATCH 4/4] KVM: x86: track actual TSC frequency from the timekeeper struct

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Date:	Fri, 19 Feb 2016 16:53:42 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>,
	KVM list <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] KVM: x86: track actual TSC frequency from the
 timekeeper struct



On 19/02/2016 15:12, Marcelo Tosatti wrote:
> 
>> >  I need to check how often the timekeeper updates the parameters.
> I'd assume once every tick, the function is called (the notifier).
> 
> But you can optimize that away by only updating the TSC frequency
> when mult/shift are updated, which should be much rarer.

Yes, exactly.  That would still not be rate limiting.

But worst case it can be a lot of adjustments, up to HZ per second...

Paolo