On Sun, 2020-03-29 at 23:37 +1000, Allan McRae via arch-dev-public wrote: > On 29/3/20 11:17 pm, Filipe Laíns wrote: > > I would also like to note that rebuilding everything with forced > > support for AVX2 or whatever won't have much effect. Most packages do > > not have workloads where it would make use sense to use these CPU > > extensions, and as such, GCC would not use them. > > That assumes we just add AVX2. Whereas, requiring a CPU supporting AVX2 > would bring other optimizations that would be used.
No, it should be true for all extensions. > As I replied earlier, AVX2 may be going too far. But is a good starting > point for discussion. If that is too far, what could we accept? > SSE4.2? AVX? Surely we can do better than pure x86_64. No, SSE4.2 is too far. For me, the minimum should be AVX. > To have a separate architecture would require automated builds, which > requires being able to sign packages automatically. And we have not > achieved database signing in 9 years.... I'm looking for a boost that > could be achieved now. No, it would not. Where is this coming from? I already build split packages with SIMD instructions, I make the PKGBUILD build for 2 architectures instead with a minimal patch. If pacman is not able to handle parallel architectures, we should fix that. I think it's a valid use case. Furthermore, if you do indeed whish to move this forward please present us with reasonable data. Take a few packages that would benefit from this, build them with the proposed architecture and show us benchmarks. I think it's gonna be very hard for you to find packages with considerable improvement but I might be wrong, please show me. Filipe Laíns
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