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[Bug c/41971] gcc 4.4 compiles 4 times slower than gcc 4.3 a huge file -O0 -g -fPIC
- From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Nov 2009 16:40:12 -0000
- Subject: [Bug c/41971] gcc 4.4 compiles 4 times slower than gcc 4.3 a huge file -O0 -g -fPIC
- References: <bug-41971-13763@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #5 from rguenth at gcc dot gnu dot org 2009-11-06 16:40 -------
Yeah, try disabling CPU frequency throttling for example. For me it's
rguenther@murzim:/tmp> /usr/bin/time gcc-4.3 -S -O0 -g -fPIC -o /dev/null
warmelt.i
13.54user 0.60system 0:15.34elapsed 92%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+120355minor)pagefaults 0swaps
rguenther@murzim:/tmp> /usr/bin/time gcc-4.3 -S -O0 -g -fPIC -o /dev/null
warmelt.i
13.50user 0.58system 0:15.37elapsed 91%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+120355minor)pagefaults 0swaps
vs.
rguenther@murzim:/tmp> /usr/bin/time gcc-4.4 -S -O0 -g -fPIC -o /dev/null
warmelt.i
17.69user 0.54system 0:19.69elapsed 92%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+110098minor)pagefaults 0swaps
rguenther@murzim:/tmp> /usr/bin/time gcc-4.4 -S -O0 -g -fPIC -o /dev/null
warmelt.i
17.58user 0.66system 0:20.02elapsed 91%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+110098minor)pagefaults 0swaps
the 4.3 compiler was built with profiled-bootstrap though.
Top time-report entries for 4.4:
parser : 1.01 ( 6%) usr 0.57 (22%) sys 1.68 ( 7%) wall
71970 kB (17%) ggc
tree gimplify : 2.52 (14%) usr 0.10 ( 4%) sys 2.98 (13%) wall
88334 kB (21%) ggc
expand : 3.30 (18%) usr 0.11 ( 4%) sys 3.79 (16%) wall
131397 kB (31%) ggc
integrated RA : 3.21 (18%) usr 0.04 ( 2%) sys 3.61 (16%) wall
3144 kB ( 1%) ggc
reload : 2.09 (11%) usr 0.05 ( 2%) sys 2.33 (10%) wall
17800 kB ( 4%) ggc
and for 4.3:
parser : 1.49 (11%) usr 0.58 (23%) sys 2.27 (13%) wall
100072 kB (28%) ggc
tree gimplify : 0.98 ( 7%) usr 0.07 ( 3%) sys 1.05 ( 6%) wall
58497 kB (16%) ggc
expand : 2.78 (20%) usr 0.14 ( 6%) sys 3.09 (17%) wall
89051 kB (24%) ggc
local alloc : 1.25 ( 9%) usr 0.02 ( 1%) sys 1.52 ( 8%) wall
3032 kB ( 1%) ggc
global alloc : 2.84 (20%) usr 0.09 ( 4%) sys 3.27 (18%) wall
18079 kB ( 5%) ggc
where the gimplify and RA changes stick out.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41971