linux-kernel - Re: [PATCH] pci: derive nearby CPUs from device's instead of bus' NUMA information

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Date:	Mon, 20 Apr 2009 14:23:47 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Ingo Molnar <mingo@...e.hu>, jbarnes@...tuousgeek.org,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pci: derive nearby CPUs from device's instead of bus' 
	NUMA information

On Mon, Apr 20, 2009 at 1:47 AM, Andreas Herrmann
<andreas.herrmann3@....com> wrote:
> On Fri, Apr 17, 2009 at 12:26:54PM -0700, Yinghai Lu wrote:
>> On Fri, Apr 17, 2009 at 9:21 AM, Ingo Molnar <mingo@...e.hu> wrote:
>> > const struct cpumask * cpumask_of_pcidev(struct pci_dev *dev)
>> > {
>> >        if (dev->numa_node == -1)
>> >                return cpumask_of_pcibus(to_pci_dev(dev)->bus);
>> >
>> >        return cpumask_of_node(dev_to_node(dev));
>> > }
>> >
>> > ? This would work fine in all cases.
>
> Yes, I think so. That's the general solution w/o additional
> "ifdefing".
>
>> you are right, dev_to_node(dev) could return -1 on 64bit, if there is
>> no memory on that node.
>
> Hmm, I thought just in the CONFIG_NUMA=n case -1 is returned.
>
> During initialization the struct device's numa_node is set to -1 and
> later on the information is inherited from the parent numa_node.
>
parent numa_node could be -1 too.

in amd_bus.c
int get_mp_bus_to_node(int busnum)
{
        int node = -1;

        if (busnum < 0 || busnum > (BUS_NR - 1))
                return node;

        node = mp_bus_to_node[busnum];

        /*
         * let numa_node_id to decide it later in dma_alloc_pages
         * if there is no ram on that node
         */
        if (node != -1 && !node_online(node))
                node = -1;

        return node;
}


YH
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