Dear Giulio, I am CCing the public Debian Med mailing list and Michael Crusoe who can help to improve the Debian package in order to have an AVX2 binary optimized.
Le jeu. 5 nov. 2020 à 15:20, Giulio Genovese <[email protected]> a écrit : > > I have noticed you are the author of the following patch for the shapeit4 > debian package: > https://salsa.debian.org/med-team/shapeit4/-/blob/master/debian/patches/use_shared_libs.patch > > I noticed that this causes shapeit4 to not use the AVX2 instruction set: > -CXXFLAG=-O3 -mavx2 -mfma > +#CXXFLAG=-O3 -mavx2 -mfma > #Portable version without avx2 (much slower) > -#CXXFLAG=-O3 > -LDFLAG=-O3 > +CXXFLAG=$(CPPFLAGS) $(CXXFLAGS) -O3 > +LDFLAG=$(LDFLAGS) -O3 > > This causes shapeit4 to run significantly slower than it could on most > systems where this package would be installed. > > I assume that the reason for this is that older CPUs do not support AVX2. Is > it really important though to support these old systems? I doubt anybody > would run such a tool on old machines. However, there might be reasons for > this decision that I might be missing so I am curious to know the goals of > this modification. > You are right, this is the Debian policy to provide binaries that respect the architecture baseline [1] to support older CPUs. And you are also right when you said nobody uses this tool on this kind of outdated CPU. Personally, I don't have time to work on that but I guess someone else in the Debian Med team would be interested? Best, Dylan [1] https://wiki.debian.org/ArchitectureSpecificsMemo#amd64
