Hi,
Would it be possible to augment the output produced in virsh
capabilities to also provide the hyperthreaded sibling of a processor?
For example the information would look something like:
<topology>
<cells num='2'>
<cell id='0'>
<cpus num='8'>
<cpu id='1' sibling='9'/>
<cpu id='3' sibling='11'/>
<cpu id='5' sibling='13'/>
<cpu id='7' sibling='15'/>
<cpu id='9' sibling='`1'/>
<cpu id='11' sibling='3'/>
<cpu id='13' sibling='5'/>
<cpu id='15' sibling='7'/>
</cpus>
</cell>
<cell id='1'>
<cpus num='8'>
<cpu id='0' sibling='8'/>
<cpu id='2' sibling='10'/>
<cpu id='4' sibling='12'/>
<cpu id='6' sibling='14'/>
<cpu id='8' sibling='0'/>
<cpu id='10' sibling='2'/>
<cpu id='12' sibling='4'/>
<cpu id='14' sibling='6'/>
</cpus>
</cell>
</cells>
</topology>
I notice that you guys are actually using some of the numactl stuff
(numa.h) to query for the cpus on a given node and I have combed
through that code to see if it provided any info about hyperthreaded
siblings but from what I can tell it does not. I have tinkered around
with the hwloc libraries (http://www.open-mpi.org/projects/hwloc/) and
have written a short program to print out each logical cpu and its
hyperthreaded sibling (see attached)
The output from it looks like so:
[root@hostname ~]# ./a.out
*** PU: 0 Hyperthreaded Sibling: 8
*** PU: 8 Hyperthreaded Sibling: 0
*** PU: 2 Hyperthreaded Sibling: 10
*** PU: 10 Hyperthreaded Sibling: 2
*** PU: 4 Hyperthreaded Sibling: 12
*** PU: 12 Hyperthreaded Sibling: 4
*** PU: 6 Hyperthreaded Sibling: 14
*** PU: 14 Hyperthreaded Sibling: 6
*** PU: 1 Hyperthreaded Sibling: 9
*** PU: 9 Hyperthreaded Sibling: 1
*** PU: 3 Hyperthreaded Sibling: 11
*** PU: 11 Hyperthreaded Sibling: 3
*** PU: 5 Hyperthreaded Sibling: 13
*** PU: 13 Hyperthreaded Sibling: 5
*** PU: 7 Hyperthreaded Sibling: 15
*** PU: 15 Hyperthreaded Sibling: 7
Would you guys ever consider adding something like this? I would be
willing to help create a patch if I had some guidance.
Thanks for your time,
Dusty Mabe
#include <hwloc.h>
// My system:
// # rpm -qa hwloc hwloc-devel
// hwloc-1.1-0.1.el6.x86_64
// hwloc-devel-1.1-0.1.el6.x86_64
//
// Command used to build
// gcc -g file.c -lhwloc
int main(void)
{
hwloc_topology_t topology;
hwloc_obj_t obj, obj2;
hwloc_topology_init(&topology);
hwloc_topology_load(topology);
// Get first PU in system
obj = hwloc_get_obj_by_type(topology, HWLOC_OBJ_PU, 0);
// Iterate through all PUs
while (obj) {
printf("*** PU: %2u PU", obj->os_index);
// Get the hyperthreaded sibling
obj2 = obj->next_sibling;
if (!obj2)
obj2 = obj->prev_sibling;
//Print the number of the sibling
printf("\t Hyperthreaded Sibling: %2u \n", obj2->os_index);
// Get the next PU in the system
obj = hwloc_get_next_obj_by_type(topology, HWLOC_OBJ_PU, obj);
}
/* Destroy topology object. */
hwloc_topology_destroy(topology);
return 0;
}
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