Hello Brice,

That makes perfect sense, and yes I do see group objects on larger systems. I was hoping to use the number of groups to see if it was safe to call hwloc_set_proc_cpubind(), but I obviously can't. I can of course simply call the Windows GetActiveProcessorGroupCount() function instead.

As I'm sure you know, the windows implementation of hwloc_set_proc_cpubind has:

hwloc_win_set_proc_cpubind(hwloc_topology_t topology...)
{
  assert(nr_processor_groups == 1);

Guess it might help to clarify when groups are assigned in the documentation.

Thank you,

David

On 29/11/2017 13:35, Brice Goglin wrote:
Hello

We only add hwloc Group objects when necessary. On your system, each
processor group contains a single NUMA node, so these Groups would not
really bring additional information about the hierarchy of resources.
If you had a bigger system with, let's say, 4 NUMA nodes, with 2 of them
in each processor groups, hwloc would report those as hwloc Group objects.

Does this help? I can clarify the FAQ if needed.

Brice



Le 29/11/2017 14:25, David Creasy a écrit :
Hello,

Thank you to all contributors to hwloc - very useful.

In the FAQ,  under the section "What are these Group objects in my
topology?" it says that they are used for "Windows processor groups".
However, I'm either not seeing this, or I'm looking in the wrong
place. On a system with two processor groups, I get:

C:\temp\hwloc-win64-build-1.11.8\bin>hwloc-info.exe
depth 0:        1 Machine (type #1)
  depth 1:       2 NUMANode (type #2)
   depth 2:      2 Package (type #3)
    depth 3:     2 L3Cache (type #4)
     depth 4:    12 L2Cache (type #4)
      depth 5:   12 L1dCache (type #4)
       depth 6:  12 L1iCache (type #4)
        depth 7: 12 Core (type #5)
         depth 8:        24 PU (type #6)

C:\temp\hwloc-win64-build-1.11.8\bin>hwloc-ls.exe
Machine (1506MB total)
   NUMANode L#0 (P#0 346MB) + Package L#0 + L3 L#0 (12MB)
     L2 L#0 (256KB) + L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0
       PU L#0 (P#0)
       PU L#1 (P#1)
     L2 L#1 (256KB) + L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1
       PU L#2 (P#2)
       PU L#3 (P#3)
     L2 L#2 (256KB) + L1d L#2 (32KB) + L1i L#2 (32KB) + Core L#2
       PU L#4 (P#4)
       PU L#5 (P#5)
     L2 L#3 (256KB) + L1d L#3 (32KB) + L1i L#3 (32KB) + Core L#3
       PU L#6 (P#6)
       PU L#7 (P#7)
     L2 L#4 (256KB) + L1d L#4 (32KB) + L1i L#4 (32KB) + Core L#4
       PU L#8 (P#8)
       PU L#9 (P#9)
     L2 L#5 (256KB) + L1d L#5 (32KB) + L1i L#5 (32KB) + Core L#5
       PU L#10 (P#10)
       PU L#11 (P#11)
   NUMANode L#1 (P#1 1160MB) + Package L#1 + L3 L#1 (12MB)
     L2 L#6 (256KB) + L1d L#6 (32KB) + L1i L#6 (32KB) + Core L#6
       PU L#12 (P#64)
       PU L#13 (P#65)
     L2 L#7 (256KB) + L1d L#7 (32KB) + L1i L#7 (32KB) + Core L#7
       PU L#14 (P#66)
       PU L#15 (P#67)
     L2 L#8 (256KB) + L1d L#8 (32KB) + L1i L#8 (32KB) + Core L#8
       PU L#16 (P#68)
       PU L#17 (P#69)
     L2 L#9 (256KB) + L1d L#9 (32KB) + L1i L#9 (32KB) + Core L#9
       PU L#18 (P#70)
       PU L#19 (P#71)
     L2 L#10 (256KB) + L1d L#10 (32KB) + L1i L#10 (32KB) + Core L#10
       PU L#20 (P#72)
       PU L#21 (P#73)
     L2 L#11 (256KB) + L1d L#11 (32KB) + L1i L#11 (32KB) + Core L#11
       PU L#22 (P#74)
       PU L#23 (P#75)

I definitely have 2 processor groups:
C:\Windows\system32>bcdedit /enum | find "group"
groupsize               6
maxgroup                Yes

And you can see this because the processor numbers above in the second
numa node start at 64. Also, calling GetActiveProcessorGroupCount()
returns 2.

I was expecting to get "2" back from:
hwloc_get_nbobjs_by_type(hwlocTopology_, HWLOC_OBJ_GROUP)

but that returns 0. Am I doing something wrong?

Thank you!

David


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