Hi,
gfortran seems to use much more memory at compile time
when I "use" larger modules that contain many symbols,
even if I "use, only" selected one. In the described
situation it needs significantly more memory than
"competitors".
The attached archive contains the following main program
and three (3) large modules to demonstrate this.
The variant with the commented lines uncommented
goes beyond 500 MB virtual memory in a Linux/x86 machine.
program main
use mo_psas, only: setup_psas
use mo_3dvar, only: obs, bg
! use mo_t_enkf, only: enkf_driver ! Uncomment to go beyond 500 MB
virt
ual mem.
implicit none
call setup_psas (obs% o, bg% grid% a, bg)
! call enkf_driver
end program main
Compiling this program with:
% gfortran -S -fmem-report -ftime-report
Memory still allocated at the end of the compilation process
Size Allocated Used Overhead
8 4096 2816 96
16 16k 13k 256
64 4096 1088 40
128 4096 768 36
256 4096 2304 32
512 64k 61k 512
2048 36k 36k 288
4096 16k 16k 128
8192 8192 8192 32
32768 416k 416k 416
8388608 8192k 8192k 32
56 4096 280 40
104 20k 17k 180
92 106M 105M 958k
80 4096 80 36
88 73M 72M 661k
24 24k 15k 312
72 4096 288 36
28 9208k 9189k 107k
112 44k 37k 396
36 4096 288 44
12 10164k 10146k 178k
40 33M 33M 364k
Total 240M 238M 2274k
String pool
entries 336041
identifiers 336041 (100.00%)
slots 524288
bytes 4934k (350k overhead)
table size 2048k
coll/search 0.6655
ins/search 0.2790
avg. entry 15.04 bytes (+/- 0.99)
longest entry 34
??? tree nodes created
(No per-node statistics)
Type hash: size 1021, 175 elements, 0.084121 collisions
DECL_DEBUG_EXPR hash: size 1021, 0 elements, 0.000000 collisions
DECL_VALUE_EXPR hash: size 2097143, 865473 elements, 1.209451 collisions
Execution times (seconds)
garbage collection : 1.56 (19%) usr 0.00 ( 0%) sys 1.54 (17%) wall
0 kB ( 0%) ggc
parser : 6.29 (78%) usr 0.78 (99%) sys 7.08 (79%) wall
25
1744 kB (100%) ggc
symout : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
TOTAL : 8.11 0.79 8.91
25
2445 kB
Extra diagnostic checks enabled; compiler may run slowly.
Configure with --disable-checking to disable checks.
The modules are extracted from a larger project and should
be sufficient to just compile the example. The project
uses MPI (mpich) which is why these symbols occur quite
frequently in the module files. Gfortran seems to handle
the present case quite inefficiently. Maybe there is a
solution that handles used modules more economically...
Cheers,
-ha
--
Summary: gfortran huge (excessive?) memory usage with large
modules
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: anlauf at gmx dot de
GCC host triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30285
