From owner-freebsd-mips@FreeBSD.ORG  Wed Jun 29 10:42:06 2011
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Date: Wed, 29 Jun 2011 16:12:04 +0530
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From: "Jayachandran C." <c.jayachandran@gmail.com>
To: Attilio Rao <attilio@freebsd.org>
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Cc: Warner Losh <imp@freebsd.org>, freebsd-mips@freebsd.org
Subject: Re: Bumping MAXCPU for MIPS configurations
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On Wed, Jun 29, 2011 at 3:10 PM, Attilio Rao <attilio@freebsd.org> wrote:
> [ Please CC me in replies as I'm not subscribed to this mailing list ]
>
> I'm planning to bump MAXCPU for all the kernel configurations
> requiring it, as long as the latest cut of largeSMP changes is
> completed.
>
> Anyway, I'm not really sure what MIPS configurations may benefit from
> a larger number of MAXCPU. Probabilly XLP should, for what I've heard,
> but I'd like to get a precise mapping between configurations that want
> to bump the number and the actual maximum number of CPUs to be
> supported.

An XLP SoC has 32 cpus (8cores x 4 hw threads per core), and 4 of
these can be interconnected to have upto 128 cpus.  We have an XLP
port running on one chip with 32cpus, but there is interest in trying
out 2 chip (64cpus) and 4 chip(128 cpus) configurations, so this is
something I want to do when I get access to multi-chip boards for
FreeBSD development.

Each XLP SoC has built-in memory controllers, network accelerator,
PCIe, UARTs, USB etc., so ideally we want to be NUMA aware rather than
doing straight SMP across all the chips. But this is an area I have
not looked into yet.

JC (Netlogic hat on).