linux-kernel - Re: [PATCH] ACPI: do not mark TSC unstable for invalid C-states

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Message-Id: <200905111703.08645.elendil@planet.nl>
Date:	Mon, 11 May 2009 17:03:07 +0200
From:	Frans Pop <elendil@...net.nl>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
	len.brown@...el.com, mingo@...e.hu, johnstul@...ibm.com
Subject: Re: [PATCH] ACPI: do not mark TSC unstable for invalid C-states

On Monday 11 May 2009, Thomas Gleixner wrote:
> commit a71e4917dc0ebbcb5a0ecb7ca3486643c1c9a6e2 (ACPI: idle:
> mark_tsc_unstable() at init-time, not run-time) marks TSC unstable
> even on non affected systems.
>
> The reason is that the state enumeration does not check the cx->valid
> flag before calling tsc_halts_in_c(), so it marks TSC unstable for any
> enumerated albeit invalid C state which is known to turn off TSC.
>
> Check cx->valid before checking whether the TSC might become unstable.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Tested-by: Frans Pop <elendil@...net.nl>

Thanks Thomas.
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