The fundamental difference is in
when this if statement is true, hwloc_setup_pu_level
finds the PU objects.
When it is false, it fails with empty topology.
I checked HWLOC_LINUX_USE_CPUINFO,
and it is not detected even when I set it from the front end.
That means the difference is whether hwloc can access
the various /sys/devices and /sys/bus files.
Additional printfs confirm that with MPI in the code,
hwloc_accessat succeeds on the various /sys/ directories,
but the overall procedure for getting PUs from these fails.
Without MPI, access to /sys/ directories fails but
the fallback hwloc_setup_pu_level works.
due to the unstable nature of the machine I'm having trouble
submitting more tests to see what goes wrong using the /sys information.
I've compiled this test, but the machine is on hold for their own testing.
I should be able to run in two days and report the results.--On Thu, Mar 22, 2012 at 6:36 PM, Brice Goglin <Brice.Goglin@inria.fr> wrote:
Le 22/03/2012 23:33, Daniel Ibanez a écrit :
> I've run this test before (didnt keep the results but can run it again).If I am reading your output correctly, all PUs are created by
> I got debug output and compared it with the output from a hwloc test
> and I noticed that my program did not show any PU objects were discovered.
> In my program the first discovered topology is just a Machine object,
> but in the hwloc program its a Machine object and 64 PU objects.
> something went wrong in PU detection...
setup_pu_level() depending on the return value of
hwloc_fallback_nbprocessors() defined in src/topology.c. Any chance you
add some printf there to understand what's going on?
hwloc_fallback_nbprocessors() would likely return 64 when things work
and 0 otherwise here.