The fundamental difference is in src/topology-linux.c:3251
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. On Thu, Mar 22, 2012 at 6:47 PM, Daniel Ibanez <dan.a.iba...@gmail.com>wrote: > 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.gog...@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). >> > I got debug output and compared it with the output from a hwloc test >> > executable >> > 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... >> >> If I am reading your output correctly, all PUs are created by >> 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. >> >> Brice >> >> > > > -- > > Dan Ibanez > -- Dan Ibanez
