linux-kernel - Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered

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Date:	Mon, 25 Feb 2008 21:27:42 -0800
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Ravikiran Thirumalai" <kiran@...lemp.com>
Cc:	"Andi Kleen" <andi@...stfloor.org>, "Ingo Molnar" <mingo@...e.hu>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	shai@...lemp.com
Subject: Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2

On Mon, Feb 25, 2008 at 8:05 PM, Ravikiran Thirumalai <kiran@...lemp.com> wrote:
> On Tue, Feb 26, 2008 at 04:46:25AM +0100, Andi Kleen wrote:
>  >> 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.
>
>  Ah!
>
>
>  >
>  >If you can't support that in your hardware you're supposed
>  >to clear it.
>
>  Hmm! How would a hardware vendor do that? That doesn't seem to be clear in
>  the BKDG. (Well, this is the problem with undocumented features :()
>
any good sign for APIC_clustered box? there is apicid between cpus
even all cpu are quadcore and fully populated?

YH
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