linux-kernel - Re: [PATCH] x86: Export tsc related information in sysfs

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Date:	Tue, 25 May 2010 17:48:08 -0700
From:	john stultz <johnstul@...ibm.com>
To:	Brian Bloniarz <bmb@...enacr.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Venkatesh Pallipadi <venki@...gle.com>, chris.mason@...cle.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Export tsc related information in sysfs

On Tue, 2010-05-25 at 20:16 -0400, Brian Bloniarz wrote:
> On 05/24/2010 09:33 PM, Brian Bloniarz wrote:
> > So what's wrong with just adding a
> > /sys/devices/system/clocksource/clocksource0/tsc_khz?
> 
> As an RFC:
> 
> Add clocksource.sys_register & sys_unregister so the
> current clocksource can add supplemental information to
> /sys/devices/system/clocksource/clocksource0/
> 
> Export tsc_khz when current_clocksource==tsc so that
> daemons like NTP can account for the variability of
> calibration results.

I think this is a bad idea, as it creates an ABI that is arch AND
machine specific, which will cause portability problems in applications
that expect the interface to be there.

thanks
-john


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