Alexander has really found a source of problems. OpenBlas is really a problem here [1]. It was fixed in Debian package on 02 Mar 2013: * Disable processor affinity. (Closes: #684338)
It means, that Debian Wheezy as well as all Ubuntus 12.10 and older are affected by the bug. We can disable the linkage of openblas for these affected distros. [1] https://bugs.debian.org/684338 [2] http://metadata.ftp-master.debian.org/changelogs/main/o/openblas/unstable_changelog Anton 2014-02-28 11:47 GMT+01:00 Eulitz, Alexander <[email protected]>: > yes, and it can be assumed that some modules that are imported in yade could > be the reason fort he problem:[1] > > "After some more googling I found the answer here. > It turns out that certain Python modules (numpy, scipy, tables, pandas, > skimage...) mess with core affinity on import. As far as I can tell, this > problem seems to be specifically caused by them linking against multithreaded > OpenBLAS libraries. > A workaround is to reset the task affinity using > os.system("taskset -p 0xff %d" % os.getpid()) > With this line pasted in after the module imports, my example now runs on all > cores. > There are also two ways to disable the CPU affinity-resetting behaviour of > OpenBLAS itself. At run-time you can use the environment variable > OPENBLAS_MAIN_FREE (or GOTOBLAS_MAIN_FREE), for example > OPENBLAS_MAIN_FREE=1 python myscript.py > Or alternatively, if you're compiling OpenBLAS from source you can > permanently disable it at build-time by editing the Makefile.rule to contain > the line > NO_AFFINITY=1 > " > > Are we compiling OpenBLAS from source? > But even if we are, why does the cpu affinity problem appear even for a built > from late 2013 which definitely worked well concerning multicore operation? > Maybe it was an update oft he openblas modul that was done by apt-get update? > > > [1] > http://stackoverflow.com/questions/15639779/what-determines-whether-different-python-processes-are-assigned-to-the-same-or-d?lq=1 > answer#25 _______________________________________________ Mailing list: https://launchpad.net/~yade-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-dev More help : https://help.launchpad.net/ListHelp
