[patch, libfortran] Adjust block size for libgfortran for unformatted reads

[Janne Blomqvist]

On Sun, Jul 7, 2019 at 11:13 PM Thomas Koenig <tkoenig@netcologne.de> wrote:
>
> Hello world,
>
> the attached patch sets the I/O block size for unformatted files to
> 2**17 and makes this, and the block size for formatted files,
> adjustable via environment variables.

Should the default be affected by the page size
(sysconf(_SC_PAGESIZE)) and/or the IO blocksize (we already fstat() a
file when we open it, so we could get st_blksize for free)?

Though one could of course argue those aren't particularly useful;
except for power, everything uses a 4k page size (?), and the IO
blocksize varies from too small (4k, ext4) to too large (1 MB, NFS (or
whatever rsize/wsize is set to), or 4 MB for Lustre).

> 2019-07-07  Thomas König  <tkoenig@gcc.gnu.org>
>
>         PR libfortran/91030
>         * gfortran.texi (GFORTRAN_BUFFER_SIZE_FORMATTED): Document
>         (GFORTRAN_BUFFER_SIZE_FORMATTED): Likewise.

One of these should be _UNFORMATTED?

-- 
Janne Blomqvist