I don't agree with the proposal, and am only interested in EPEL, but: Kevin Kofler <kevin.kof...@chello.at> writes:
> I disagree with ANY raised vector instruction requirement, considering that: > * it would make Fedora incompatible with some hardware out there, That's already so for hardware which is at least of similar age to SSE2-only x86_64, i.e. POWER7; my build logs show -mcpu=power8. > * the performance increase to be had is marginal, given that we are mostly > talking about code written in C or C++ without even compiler vectorization > (-ftree-vectorize) turned on, I forget the details, but libxsmm is something that depends on an instruction introduced with SSE3, and is a good example of portable performance engineering over a wide range of (x86_64) processors. > * there are already mechanisms for runtime feature detection, which are > already widely used in those few packages that can actually benefit from > the vector instructions (because they are performance-sensitive and > because they have handwritten assembly or vector intrinsics code), I disagree that dynamic dispatch is sufficiently widely used in scientific code (probably can't be with Fortran). Also recent GCC can provide decent performance for specific targets without target-specific programming. BLIS' portable C version DGEMM got around 60%(?) the speed of the hand-tuned implementation built for haswell, as reported somewhere in the BLIS issues. For people who don't know, DEGMM (generalized matrix-matrix multiplication) is as SIMD-intensive as it gets, with high enough floating point intensity relative to memory access for large enough dimensions; non-matrix-matrix linear algebra typically doesn't if it doesn't fit in cache. _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org
