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Re: [PATCH] x86/NUMA: improve memnode_shift calculation for multi node system


  • To: Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Fri, 30 Sep 2022 12:50:10 +0200
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
  • Delivery-date: Fri, 30 Sep 2022 10:50:20 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 30.09.2022 12:03, Roger Pau Monné wrote:
> On Fri, Sep 30, 2022 at 10:36:20AM +0200, Jan Beulich wrote:
>> On 30.09.2022 10:25, Roger Pau Monné wrote:
>>> On Tue, Sep 27, 2022 at 06:20:35PM +0200, Jan Beulich wrote:
>>>> @@ -413,14 +414,37 @@ acpi_numa_memory_affinity_init(const str
>>>>           node, pxm, start, end - 1,
>>>>           ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE ? " (hotplug)" : "");
>>>>  
>>>> -  node_memblk_range[num_node_memblks].start = start;
>>>> -  node_memblk_range[num_node_memblks].end = end;
>>>> -  memblk_nodeid[num_node_memblks] = node;
>>>> +  /* Keep node_memblk_range[] sorted by address. */
>>>> +  for (i = 0; i < num_node_memblks; ++i)
>>>> +          if (node_memblk_range[i].start > start ||
>>>> +              (node_memblk_range[i].start == start &&
>>>
>>> Maybe I'm confused, but won't .start == start means we have
>>> overlapping ranges?
>>
>> Yes, except when a range is empty.
> 
> Hm, OK.  Won't overlapping ranges be bad if not empty?

They are and ...

> Shouldn't Xen complain if it finds overlapping ranges, or that's taken
> care somewhere else?

... we do, elsewhere. Still I'd like this code to be generic, at the very
least to - as said - deal with empty ranges as well. It didn't seem
indicated to me to special case empty ranges here, when the code is more
clear when written in a more generic manner.

Jan



 


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