netdev - Re: [PATCH] irq: Add node_affinity CPU masks for smarter irqbalance hints

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Message-ID: <20091125115019.GG29096@one.firstfloor.org>
Date:	Wed, 25 Nov 2009 12:50:19 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	David Miller <davem@...emloft.net>,
	peter.p.waskiewicz.jr@...el.com, peterz@...radead.org,
	arjan@...ux.intel.com, yong.zhang0@...il.com,
	linux-kernel@...r.kernel.org, arjan@...ux.jf.intel.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH] irq: Add node_affinity CPU masks for smarter irqbalance hints

On Wed, Nov 25, 2009 at 12:35:03PM +0100, Eric Dumazet wrote:
> > You seem to only have 8 CPUs (one socket) Normally a dual socket nehalem
> > should have 16 with HyperThreading enabled.
> > 
> > For some reason the BIOS is not reporting the other CPU.
> > 
> > You could double check with acpidmp / iasl -d if that's
> > what the BIOS really reports, but normally it should work.
> > 
> 
> Good Lord, I had a CONFIG_NR_CPUS=16 in my .config.

That should be enough for a two socket (2S x 4C x 2T) today,
but of course that will eventually change too.

> Changing to to 32 or 64 seems better :)

That looks weird. It should have worked with CONFIG_NR_CPUS==16 too,
because you only have 16 CPUs and the NR_CPUS should affect APIC
ranges etc.

Something still fishy. I would properly report it.

BTW kernel should give some error message in any case when
there are not enough CPUs I guess. 

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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