See the following timings: If I start Sage with OMP_NUM_THREADS=1, a particular computation takes 1.52 cpu seconds and 1.56 wall seconds.
The same computation without OMP_NUM_THREADS set takes 12.8 cpu seconds and 1.69 wall seconds. This is particularly devastating when I'm running with @parallel to use all of my cpu cores. My guess is that this is Linbox related, since these computations do some exact linear algebra, and Linbox can do some multithreading, which perhaps uses OpenMP. jb12407@lmfdb1:~$ OMP_NUM_THREADS=1 sage [...] SageMath version 7.4.beta6, Release Date: 2016-09-24 [...] Warning: this is a prerelease version, and it may be unstable. [...] sage: %time M = ModularSymbols(5113, 2, -1) CPU times: user 509 ms, sys: 21 ms, total: 530 ms Wall time: 530 ms sage: %time S = M.cuspidal_subspace().new_subspace() CPU times: user 1.42 s, sys: 97 ms, total: 1.52 s Wall time: 1.56 s jb12407@lmfdb1:~$ sage [...] SageMath version 7.4.beta6, Release Date: 2016-09-24 [...] sage: %time M = ModularSymbols(5113, 2, -1) CPU times: user 570 ms, sys: 18 ms, total: 588 ms Wall time: 591 ms sage: %time S = M.cuspidal_subspace().new_subspace() CPU times: user 3.76 s, sys: 9.01 s, total: 12.8 s Wall time: 1.69 s -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
