[Bug libfortran/91030] Poor performance of I/O -fconvert=big-endian

[dje at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91030

--- Comment #32 from David Edelsohn <dje at gcc dot gnu.org> ---
If the performance measured by Jerry is hitting limits of the 4 x 32KiB L1
D-Cache of the Ryzen 2500U, then the system has bigger problems than FORTRAN
I/O buffer size.

What is the target audience / market for GNU FORTRAN?

FORTRAN primarily is used for numerically intensive computing and HPC.  This
issue was discovered through an experiment by an organization that perform huge
HPC simulations and inquired about the performance of GNU FORTRAN.  I suggest
that GNU FORTRAN implement defaults appropriate for HPC systems if it wants to
increase adoption in large-scale commercial environments.

If we can find some heuristics that allow GNU FORTRAN to distinguish between
consumer and commercial systems, that would be ideal.