From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [PATCH] ACPI: Idle C-states disabled by max_cstate should not disable the TSC Date: Fri, 15 May 2009 10:27:55 +0200 (CEST) Message-ID: References: <200905110226.50115.elendil@planet.nl> <4A0855A5.8040109@tut.fi> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from www.tglx.de ([62.245.132.106]:53046 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756481AbZEOI3U (ORCPT ); Fri, 15 May 2009 04:29:20 -0400 In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Len Brown Cc: Venkatesh Pallipadi , Janne Kulmala , Frans Pop , Linux Kernel Mailing List , Steven Rostedt , Ingo Molnar , johnstul@us.ibm.com, linux-acpi@vger.kernel.org On Fri, 15 May 2009, Len Brown wrote: > From: Len Brown > > Processor idle power states C2 and C3 stop the TSC on many machines. > Linux recognizes this situation and marks the TSC as unstable: > > Marking TSC unstable due to TSC halts in idle > > But if those same machines are booted with "processor.max_cstate=1", > then there is no need to validate C2 and C3, and no need to > disable the TSC, which can be reliably used as a clocksource. > > Signed-off-by: Len Brown Acked-by: Thomas Gleixner > --- > drivers/acpi/processor_idle.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c > index e39a40a..e65476f 100644 > --- a/drivers/acpi/processor_idle.c > +++ b/drivers/acpi/processor_idle.c > @@ -582,7 +582,7 @@ static int acpi_processor_power_verify(struct acpi_processor *pr) > > pr->power.timer_broadcast_on_state = INT_MAX; > > - for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) { > + for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) { > struct acpi_processor_cx *cx = &pr->power.states[i]; > > switch (cx->type) { > -- > 1.6.3.1.9.g95405b >