Le 30/10/2010 00:01, Jirka Hladky a écrit : > On Friday, October 29, 2010 10:59:25 pm Brice Goglin wrote: > >> Le 29/10/2010 21:57, Jirka Hladky a écrit : >> >>> Hi Samuel, >>> >>> I have attached the output of >>> tests/linux/gather-topology.sh `uname --kernel-release`_`uname -- >>> nodename`_gather-topology >>> >>> I'm sorry for the long delay - systems has been used by somebody else, I >>> had to wait for it to be free. >>> >>> System is running kernel 2.6.18-227.el5 (RHEL 5.6). ia64 is not supported >>> on RHEL 6.0 so I cannot really test it on the new kernel. >>> >>> It would be really interesting if you can recognize if it's a kernel bug >>> or hwloc problem. >>> >> /sys/devices/system/cpu/cpu*/cache/index4/shared_cpu_map contains an >> empty map. This index4 is a L3 cache. But this map means that this cache >> is near none of the cores... The instruction L2 has the same problem >> (index3 instead of 4). This is a kernel bug. >> >> But, we already have a dedicated work-around in hwloc >> (src/topology-linux.c): >> if (hwloc_bitmap_weight(cacheset) < 1) >> /* mask is wrong (happens on ia64), assumes it's not shared */ >> hwloc_bitmap_only(cacheset, i); >> >> This work-around worked fine on old itaniums since they had one L3, one >> L2 and one L1 per core. Your machine has hyperthreading, so our >> work-around creates one L3 per thread, while L1 and L2 (properly >> reported by the kernel) are core-specific. Maybe hwloc should just >> ignore caches with invalid shared_cpu_map. >> >> Brice >> >> _______________________________________________ >> hwloc-devel mailing list >> hwloc-de...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-devel >> > > Hi Brice, > > thanks for looking into it! I'm going to open a BZ for it and put you on the > Cc. >
Thanks. > BTW, is there some documentation on /sys/devices/system/cpu/* tree? > There's some doc in Documentation/ABI/*/sysfs-devices-* inside the kernel source tree. Brice
