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Re: [Xen-devel] [PATCH] xend: Fix non-contiguous NUMA node assignment

To: Andre Przywara <andre.przywara@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xend: Fix non-contiguous NUMA node assignment
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Sun, 17 Jan 2010 18:55:42 +0000
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I had a go myself: see c/s 20817. This keeps nr_nodes as well as
max_node_id, and continues to use it where it seemed to make sense to do so.

 -- Keir

On 17/01/2010 17:48, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

> nr_nodes was always num_online_nodes() returned by Xen -- not accounting for
> holes in node id space. Hance I emulated that behaviour from the Python
> extension package. If what you actually want everywhere in the Python code
> is max_node_id, then please remove the nr_nodes code from xc.c and all
> references to it from the Python code. I agree that using max_node_id seems
> more correct than nr_nodes -- the intention was for someone to plumb that
> new field properly into the Python code anyway.
> 
>  -- Keir
> 
> On 15/01/2010 13:28, "Andre Przywara" <andre.przywara@xxxxxxx> wrote:
> 
>> Hi,
>> 
>> it seems that I missed a point in this whole addition of max_node_id. I
>> see the difference in the Xen HV part, so nr_nodes got replaced with
>> max_node_id in physinfo_t (and xc_physinfo_t, respectively).
>> But where does this value help in xend? There is no single Python
>> reference to the physinfo()'s max_node_id field, instead all functions
>> use the old (but now bogus) nr_nodes variable.
>> So in the attached patch I kept the xc.physinfo() returned dictionary
>> with only a nr_nodes field, calculated by simply adding 1 to max_node_id
>> from libxc. Empty nodes can (and will) be detected by iterating through
>> the node_to_cpus and node_to_memory lists.
>> Nodes without memory should not be considered during guest's memory
>> allocation, but will be used for further CPU affinity setting if the
>> number of VCPUs exceeds the number of cores per node.
>> 
>> Please correct me if I am totally wrong on this, but this seems to work
>> much better in my case.
>> 
>> Regards,
>> Andre.
>> 
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> 
> 
> 
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