linux-kernel - Re: [URGENT rfc patch 0/3] tsc clocksource bug fix

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Message-ID: <CAFTL4hy24+=2++CN5rBhn9v+pvxR+tTja9Z-wRLSS__LGQBWaQ@mail.gmail.com>
Date:	Fri, 5 Jul 2013 16:23:33 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Alex Shi <alex.shi@...el.com>, tglx@...utronix.de,
	hpa@...ux.intel.com, tim.c.chen@...ux.intel.com,
	linux-kernel@...r.kernel.org, andi.kleen@...el.com, mingo@...e.hu
Subject: Re: [URGENT rfc patch 0/3] tsc clocksource bug fix

2013/7/4 Peter Zijlstra <peterz@...radead.org>:
> On Thu, Jul 04, 2013 at 01:34:13PM +0800, Alex Shi wrote:
>
>> If the tsc is marked as constant and nonstop, could we set it as system
>> clocksource when do tsc register? w/o checking it on clocksource_watchdog?
>
> I'd not do that; the BIOS can still screw you over, we need some validation.
>
> That said; we do need means to disable the clocksource watchdog -- although I
> suppose Frederic might already have provided this for this NOHZ efforts when I
> wasn't looking.

Nope, I haven't touched that. I prefer not to fiddle with unstable
clocksource for now :)

As for unstable TSCs, if sched_clock_tick() needs to be fed, we simply
don't stop the tick.
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