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Date: Fri, 04 Mar 2005 10:48:00 -0000
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From: "Thomas dot Koenig at online dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libfortran/16339] Unformatted i/o on large arrays inefficient
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------- Additional Comments From Thomas dot Koenig at online dot de  2005-03-04 10:47 -------
This is really _very_ inefficient, by a factor of 20.

Some test numbers:

$ g77 write-record.f
$ time ./a.out

real    0m1.819s
user    0m1.774s
sys     0m0.044s
$ gfortran write-record.f
$ time ./a.out

real    0m43.723s
user    0m9.003s
sys     0m34.571s
$ cat write-record.f
      program main
      integer n
      parameter (n=10000000)
      real a(n)
      write (10) (a(i),i=1,n)
      end
$ gfortran -v
Using built-in specs.
Target: ia64-unknown-linux-gnu
Configured with: ../gcc-4.1-20050227/configure --prefix=/home/zfkts
--enable-languages=c,f95
Thread model: posix
gcc version 4.1.0 20050227 (experimental)

By comparison:
$ ifort write-record.f
$ time ./a.out

real    0m0.117s
user    0m0.001s
sys     0m0.116s


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16339