linux-kernel - Re: [PATCH resend] clocksource: Defer override invalidation unless clock is unstable

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Message-ID: <CAEPKNT+L=MGOZKdi0AqiRuJRg1tv-8nPnJyM6Y=htrwzY7LGBQ@mail.gmail.com>
Date:	Fri, 5 Aug 2016 14:38:55 -0400
From:	Kyle Walker <kwalker@...hat.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH resend] clocksource: Defer override invalidation unless
 clock is unstable

Good evening John,

On Wed, Jul 27, 2016 at 10:29 AM, Kyle Walker <kwalker@...hat.com> wrote:
> The issue I'm running into is that the override is not HRT compatible yet.
> Though it will be later in the boot process, unless the clocksource watchdog
> marks the clocksource as unstable.
>
> The issue with the current implementation is that the override_name value is
> disabled when the tsc is first checked, before the watchdog has a chance to
> check it and mark it stable or unstable.
>
> Without patch:
> $ dmesg | grep -e clocksource
> <snip>
> clocksource: refined-jiffies: <snip>
> Kernel command line: <snip> clocksource=tsc
> clocksource: hpet: <snip>
> clocksource: xen: <snip>
> clocksource: jiffies: <snip>
> clocksource: Switched to clocksource xen
> clocksource: acpi_pm: <snip>
> tsc: Refined TSC clocksource calibration: 2394.399 MHz
>
> clocksource: tsc: <snip>
> clocksource: Override clocksource tsc is not HRT compatible - <snip>
>
>
> With patch:
> $ dmesg | grep -e clocksource
> <snip>
> clocksource: refined-jiffies:<snip>
> Kernel command line: <snip> clocksource=tsc
> clocksource: hpet: <snip>
> clocksource: xen: <snip>
>
> clocksource: jiffies: <snip>
> clocksource: Switched to clocksource xen
> clocksource: acpi_pm: <snip>
> tsc: Refined TSC clocksource calibration: 2394.461 MHz
> clocksource: tsc: <snip>
> clocksource: Override clocksource tsc is not currently HRT compatible
> - deferring
> clocksource: Switched to clocksource tsc
>

Is there anything else needed from my end? Please let me know if there is
any further information or clarification I can provide.

Have a great evening!
-- 
Kyle Walker