[Bug libfortran/23363] New: gfortran 30 x slower that g77 on random I/O

[dir at lanl dot gov]

I found some of my programs running extremely slow with gfortran. Here is a test
case that shows the problem -

[dranta:~/tests/gfortran-D] dir% g77 -o rdiska rdiska.f
[dranta:~/tests/gfortran-D] dir% time rdiska
0.010u 0.080s 0:00.20 45.0%     0+0k 0+1io 0pf+0w
[dranta:~/tests/gfortran-D] dir% gfortran -o rdiska rdiska.f
[dranta:~/tests/gfortran-D] dir% time rdiska
STOP 0
8.160u 29.010s 0:37.13 100.1%   0+0k 0+1io 0pf+0w
[dranta:~/tests/gfortran-D] dir% cat rdiska.f
      program main
      implicit integer(a-z)
      dimension w(16384)
      common/frfcm1/mxfrf,ifrf,buflen,fcsize,dskloc ,curlen,kop,ier
      ncpw=4
      buflen=16384
      lrecl=ncpw*buflen                                              
      open (3,access='direct',form='unformatted'
     1,recl=lrecl,status='unknown')
      do 10 i=1,200
      call wdiska(3,w,16384,(i-1)*buflen);
   10 continue
      do 20 i=1,200
      call rdiska(3,w,16384,(200-i)*buflen);
   20 continue
      stop
      end
      subroutine rdiska (lus,w,nw,da)
      implicit integer(a-z)
      dimension w(nw)
      common/frfcm1/mxfrf,ifrf,buflen,fcsize,dskloc ,curlen,kop,ier
      lda=da/buflen+1
      read (lus,rec=lda,iostat=ios) w
      return
      entry wdiska(lus,w,nw,da)
      lda=da/buflen+1
      write (lus,rec=lda) w
      return
c
      end

-- 
           Summary: gfortran 30 x slower that g77 on random I/O
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dir at lanl dot gov
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: powerpc-apple-darwin7.9.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23363