linux-kernel - Re: [RESEND] Fast TSC calibration fails with v3.14-rc1 and later

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Message-ID: <1394465314.12752.18.camel@x220>
Date:	Mon, 10 Mar 2014 16:28:34 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Julian Wollrath <jwollrath@....de>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RESEND] Fast TSC calibration fails with v3.14-rc1 and later

On Mon, 2014-03-10 at 15:06 +0100, Thomas Gleixner wrote:
> And how is this related to Julians observation, that fast calibration
> works in 3.13, but stopped to work in 3.14-rc ?

In the rest of my message - which you didn't quote - I stated that "the
error need not be v3.14-rc1 specific. But perhaps something changed in
v3.14-rc1 that makes it easier to trigger that error. I haven't
checked". (I didn't add that, in my experience, this message is not seen
at every boot.) So I'm basically advising Julian to double check whether
this is really a change in behavior between v3.13 and v3.14-rc1. But
perhaps Julian already did.

And I'm also telling Julian that, as far as I can tell, there's no
reason to print this message at KERN_ERR level because what subsequently
will happen is that an alternative calibration strategy is tried. So a
failure of fast TSC calibration is apparently not so severe. See
https://lkml.org/lkml/2012/9/24/221 . Is that analysis incorrect?

Thanks,

Paul Bolle

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