linux-kernel - Re: pvclock time drifting backward

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Message-ID: <4eda127551d240b9e19c1eced16ad6f6ed5c2f80.camel@infradead.org>
Date: Tue, 25 Mar 2025 11:07:34 +0000
From: David Woodhouse <dwmw2@...radead.org>
To: Sean Christopherson <seanjc@...gle.com>, Ming Lin <minggr@...il.com>
Cc: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>, 
	linux-kernel@...r.kernel.org
Subject: Re: pvclock time drifting backward

On Mon, 2025-03-24 at 15:54 -0700, Sean Christopherson wrote:
> 
> David can confirm, but I'm pretty sure the drift you are observing is addressed
> by David's series to fix a plethora of kvmclock warts.
> 
> https://lore.kernel.org/all/20240522001817.619072-1-dwmw2@infradead.org

Yes, that looks like exactly the problem my series is addressing. We
shouldn't update the pvclock so often. And if/when we do, we shouldn't
clamp it to some *other* clock which progresses at a different rate to
the pvclock, because that causes steps in the pvclock.



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