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

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Message-ID: <dd1c0508-5570-4e65-89c0-4037eb210646@default>
Date:	Tue, 18 May 2010 12:00:34 -0700 (PDT)
From:	Dan Magenheimer <dan.magenheimer@...cle.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Ingo Molnar <mingo@...e.hu>, chris.mason@...cle.com,
	linux-kernel@...r.kernel.org
Subject: RE: [PATCH] x86: Export tsc related information in sysfs

> From: H. Peter Anvin [mailto:hpa@...or.com]
> Subject: Re: [PATCH] x86: Export tsc related information in sysfs
> 
> On 05/18/2010 10:49 AM, Dan Magenheimer wrote:
> >
> > (Though I expect tglx/arjan/andi/mingo to disagree with this proposal
> > for similar reasons as the original one that started this thread...)
> 
> I'll add another reason to disagree: exporting these as sysfs variables
> is non-atomic, but these are really only useful when atomically read as
> a unit.

Which "these"?  The counters?  I would think the primary use
of the counters is to diagnose extreme problem cases, not
to differentiate whether a system or process did exactly
27 vs 28 rdtsc's, so I don't see why atomic read is at all
necessary.

Or did I miss your point entirely?
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