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[Bug libfortran/37754] [4.4 Regression] READ I/O Performance regression from 4.3 to 4.4
- From: "jvdelisle at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 7 Oct 2008 03:58:51 -0000
- Subject: [Bug libfortran/37754] [4.4 Regression] READ I/O Performance regression from 4.3 to 4.4
- References: <bug-37754-6019@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #2 from jvdelisle at gcc dot gnu dot org 2008-10-07 03:58 -------
strace shows no difference in number of system calles between 4.3 and 4.4.
gprof has some interesting things to see.
With 4.4:
% cumulative self self total
time seconds seconds calls ms/call ms/call name
30.93 0.54 0.54 data_transfer_init
8.67 0.69 0.15 fflush
8.09 0.83 0.14 get_external_unit
6.94 0.95 0.12 finalize_transfer
6.65 1.06 0.12 next_char
6.36 1.17 0.11 fd_read
3.47 1.23 0.06 memcpy
2.60 1.28 0.05 _gfortran_st_read
2.31 1.32 0.04 fd_sfree
With 4.3:
% cumulative self self total
time seconds seconds calls ms/call ms/call name
26.25 0.42 0.42 data_transfer_init
12.50 0.62 0.20 fflush
9.38 0.77 0.15 finalize_transfer
6.25 0.87 0.10 1 100.00 100.00 MAIN__
6.25 0.97 0.10 get_external_unit
5.94 1.07 0.10 next_char
4.69 1.14 0.08 _gfortran_st_read
2.81 1.19 0.05 fd_alloc_r_at
2.50 1.23 0.04 _gfortrani_library_start
2.19 1.26 0.04 _gfortran_st_read_done
I will try some of my more aggressive I/O tests and report back.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37754