linux-kernel - Re: [patch] x86: unify/rewrite SMP TSC sync code

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Date:	Fri, 24 Nov 2006 18:56:12 -0800
From:	Wink Saville <wink@...ille.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Andi Kleen <ak@...e.de>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...l.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch] x86: unify/rewrite SMP TSC sync code

Ingo Molnar wrote:
> * Andi Kleen <ak@...e.de> wrote:
> 
> a new CPU is added. If the TSC isnt sync on SMP then it quickly gets 
> pretty messy, and we should rather take a look at /why/ these apps are 
> using RDTSC.
> 
> 	Ingo
> -

I use RDTSC in get a cheap method of measuring time. What other choices are
there for a low overhead high frequency time source?

By low overhead a kernel call is way to expensive, I want to minimally impact
the code and have many of these calls through out the code. One of the
ways I use it is to instrument multi-threaded applications and then use
the TSC to compare when actions occur between threads. i.e. I use it as a
time stamp counter and neither precision or accuracy is too important.
On the other hand the more precise and accurate the better:)

Cheers,

Wink Saville

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