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Date: Mon, 9 Nov 2009 13:38:24 +0100 From: Andi Kleen <andi@...stfloor.org> To: Andre Przywara <andre.przywara@....com> Cc: Andi Kleen <andi@...stfloor.org>, Linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: x86/NUMA: Reason for ignoring too small NUMA nodes? On Mon, Nov 09, 2009 at 01:27:15PM +0100, Andre Przywara wrote: > while experimenting with a system with a memory-less NUMA node I stumbled > upon code in the Linux kernel which ignores nodes containing less than a > certain amount of RAM, obviously to fix systems with a buggy BIOS. > Can you elaborate on this? What kind of incorrect entry have you seen? > To correctly map the memory less node I did a patch to accept at least > nodes with exactly zero bytes of memory (read: no SRAT memory entry), was > this special condition also present in the buggy machines? It was a misparsed numa node, not zero. I don't remember if the bug was in Linux or in the BIOS. This was a sanity check to catch all such cases. I haven't seen misparsed nodes for quite some time, so in theory it could be removed I guess. Zero size node were back then not supported in the VM. I still think the concept doesn't make too much sense: a memory range without memory (and it bitrots all the time even today, see recent patches) -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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