Date: Tue, 26 Feb 2008 04:46:25 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Ravikiran Thirumalai <kiran@scalemp.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>, Andi Kleen <andi@firstfloor.org>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       shai@scalemp.com
Subject: Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2
Message-ID: <20080226034625.GE21577@one.firstfloor.org>
References: <200802210258.45011.yinghai.lu@sun.com> <200802221102.31019.yinghai.lu@sun.com> <47BF1BD9.4020808@firstfloor.org> <200802232148.43255.yinghai.lu@sun.com> <20080224122903.GC13637@one.firstfloor.org> <20080225190819.GE3143@localdomain> <86802c440802251405w7025a8b2na5fde4dcbf56067e@mail.gmail.com> <20080226033945.GJ3143@localdomain>
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> I don't quite understand the purpose of the patch to begin with.  Looking at
> the current x86 git tree, apic_is_clustered_box is used only to determine if
> tsc is synchronized on the platform.  The AMD docs  imply that TSC's are not
> guaranteed to be synced across cores between nodes -- Opteron BKDG for
> family 10h, Section 2.9.4:

After long discussions with AMD they determined the CPUID flag
for sync RDTSC will imply synchronization between nodes.

If you can't support that in your hardware you're supposed
to clear it.

-Andi
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