linux-kernel - Re: [v1 0/9] Early boot time stamps for x86

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Message-ID: <e8e2a870-fea9-54d8-3107-928032911df3@oracle.com>
Date:   Wed, 22 Mar 2017 20:02:34 -0400
From:   Pasha Tatashin <pasha.tatashin@...cle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, mingo@...hat.com,
        tglx@...utronix.de, hpa@...or.com
Subject: Re: [v1 0/9] Early boot time stamps for x86

On 2017-03-22 16:27, Peter Zijlstra wrote:
> On Wed, Mar 22, 2017 at 04:24:16PM -0400, Pavel Tatashin wrote:
>> Last week I sent out patches to enable early boot time stamp on SPARC, that
>> work is now under review:
>> http://www.spinics.net/lists/sparclinux/msg17372.html
>>
>> This is continuation for that work, but adding early boot time stamps
>> support for x86 machines.
>
> *groan*, so we get an even bigger trainwreck when TSC is fscked?
>

Hi Peter,

I am not sure what you mean. If tsc is not reliable, the worst case is 
that during early boot the timestamps won't be as accurate as the 
timestamps that are enabled once we initialize some other clock sources.

In either way, if you look at the way I enabled early timestamps, it is 
really narrowed down to work only on modern hardware with stable tsc. 
(Nehalem and later)

Thank you,
Pasha