[Bug libfortran/50016] [4.7 Regression] Drastic I/O performance regression on Windows

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50016

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-10-18
   Target Milestone|4.6.2                       |4.7.0
            Summary|[4.6/4.7 Regression]        |[4.7 Regression] Drastic
                   |Drastic I/O performance     |I/O performance regression
                   |regression on Windows       |on Windows
     Ever Confirmed|0                           |1

--- Comment #15 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-10-18 13:08:22 UTC ---
[4.6] FIXED (comment 14) or at least mitigated the issue on the 4.6 branch - in
time for the 4.6.2 release. See also
http://gcc.gnu.org/ml/fortran/2011-10/msg00132.html

 * * *

For the 4.7 trunk, we are still discussion, when to call _commit.
MinGW/MinGW-w64 users of GCC 4.7 could consider using that patch in the
meanwhile.

Start of the discussion:
  http://gcc.gnu.org/ml/fortran/2011-10/threads.html#00079

Patch version 1: Keep _commit only for FLUSH() subroutine/statement
  http://gcc.gnu.org/ml/fortran/2011-10/msg00132.html

Patch version 2: Remove _commit completely, use internal file-size when
inquiring open files. (The latter is an independent separate issue, but was the
reason for adding _commit at the first place; cf. PR 44698.)
  http://gcc.gnu.org/ml/fortran/2011-10/msg00094.html

 * * *

Xunxun: Thanks for the report and sorry for making the Windows version that
slow and for the two-months delay in fixing it.