Date: Sun, 30 Mar 2008 21:18:21 -0500
From: Jack Steiner <steiner@sgi.com>
To: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
       tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC 8/8] x86_64: Support for new UV apic
Message-ID: <20080331021821.GC20619@sgi.com>
References: <20080324182122.GA28327@sgi.com> <87abknhzhd.fsf@basil.nowhere.org> <20080325175657.GA6262@sgi.com> <20080326073823.GD3442@elte.hu> <86802c440803301323q5c4bd4f4k1f9bdc1d6b1a0a7b@mail.gmail.com> <20080330210356.GA13383@sgi.com> <20080330211848.GA29105@one.firstfloor.org> <86802c440803301629g6d1b896o27e12ef3c84ded2c@mail.gmail.com>
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> 
> if the calling path like GET_APIC_ID is keeping checking if it is UV
> box after boot time, that may not good.
> 
> don't need make other hundreds of machine keep running the code only
> for several big box all the time.
> 
> YH


I added trace code to see how often GET_APIC_ID() is called. For
my 8p AMD box, the  function is called 6 times per cpu during boot.
I have not seen any other calls to the function after early boot
although I'm they occur under some circumstances.

Can you think of a workload where the frequency of calls is
high enough to be significant??

--- jack
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