Le 22/02/2012 07:36, Eugene Loh a écrit : > On 2/21/2012 5:40 PM, Paul H. Hargrove wrote: >> Here are the first of the results of the testing I promised. >> I am not 100% sure how to reach the code that Eugene reported as >> problematic, > I don't think you're going to see it. Somehow, hwloc on the config in > question thinks there is no socket level and returns num_sockets==0. > If you can run something successfully, your platform won't show the > issue.
(Eugene sent hwloc info offlist) This is an "interesting" case. Last time I used a RHEL4 2.6.9 kernel, it had no sysfs topology info, but there was some "physical package" info in /proc/cpuinfo. Yours has nothing. Maybe because it's an AMD and/or single-core-processor based system. sysfs still has NUMA topology info (this was added to the kernel around 2.5 iirc) so we get 2 NUMA nodes with one core each but no socket at all. We could assume there one socket per NUMA node but that's a risky hack. Anyway, we have seen other systems (mostly non-Linux) where lstopo reports nothing interesting (only one machine object with multiple PU children). So numsockets==0 isn't really uncommon. Replacing 0 with 1 will likely work for your computations. Make sure the code isn't going to use the first hwloc socket object later, it would get NULL obviously. Brice
