Currently the gfortran IO library is based on a design called the "Alloc Stream
Facility" (ASF), described in the paper
* "Exploiting the advantages of mapped files for stream I/O",
* O. Krieger, M. Stumm and R. Umrau, "Proceedings of the 1992 Winter
* USENIX conference", p. 27-42.
The idea is to present an interface that avoids an extra copy when used
together with mmap, and the application uses ASF directly instead of
read/write. However, Fortran IO follows a traditional read/write model, and
thus the buffer copy is still needed in the library.
Thus, ASF makes the IO library unnecessarily complex and doesn't improve
performance. If ASF would provide any real benefit, it could be implemented in
the C library or the kernel, and any program using read/write, including the
gfortran IO library, would benefit.
--
Summary: Eventually get rid of the Alloc Stream Facility
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: libfortran
AssignedTo: jb at gcc dot gnu dot org
ReportedBy: jb at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25561
