This is results of simple CFLAGS test. Maybe it will be useful for someone so I post it here. I was wonder if results for old processors will be same as for the fast ones so I made this simple test. You can compare this test with Javier Villavicencio's (http://article.gmane.org/gmane.linux.gentoo.user/51881)).
I was compiling gnuchess (http://www.gnu.org/software/chess/chess.html) with various CFLAGS settings. For each compiled gnuchess I ran these commands: ./gnuchess depth 8 go quit and wrote down duration of "go" command (gnuchess prints it). Following numbers are average values of five (or more) values. Each test was performed two times. One in X with many processes running (mostly sleeping). Second in console with minimum of processes and with niced priority (nice -18) of gnuchess. Values are in seconds. In parentheses is place (best is on 1st place, worst on 14th place). Lines marked with "X" are values from test in X environment and "C" lines are values from console test. Here are the results: 1. Without optimizations X 22.12 (14) C 17.65 (14) [slowest of course - 14th place] 2. "Basic" O2 test (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer): X 16.73 (8, 9) C 13.29 (6) [much better] 3. Changed to O3 (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O3 -fomit-frame-pointer): X 17.23 (12) C 15.25 (13) [slower than O2 - same result as in Javier Villavicencio's test] 4. Trying O3 being faster (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O3 -fomit-frame-pointer -falign-functions=4 -falign-jumps=4): X 16.62 (7) C 13.50 (7) [almost same as "basic" O2] 5. Don't give up with O3 (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O3 -fomit-frame-pointer -falign-functions=4 -falign-jumps=4 -fforce-addr): X 17.09 (11) C 14.39 (12) [bad results :-(] 6. Piece of O3 in O2 (O3 implies -frename-registers) (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer -frename-registers): X 16.44 (4) C 13.19 (5) [pretty fast - as in Javier Villavicencio's test] 7. Trying somethin else (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer -falign-functions=4 -falign-jumps=4): X 16.25 (1) C 13.11 (3, 4) [bingo! first place in X environment; also close to second and first place in console] 8. Combination of two previous (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer -frename-registers -falign-functions=4 -falign-jumps=4): X 16.73 (8, 9) C 14.03 (10) [aargh! slow; why???] 9. Trying -fforce-addr (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer -fforce-addr): X 18.33 (13) C 13.74 (9) [slower - like with O3; Javier Villavicencio's test shows same results; this is much slower in X (almost last place) - why?] 10. Just for a record (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2 -fomit-frame-pointer -fforce-addr -frename-registers): X 17.02 (10) C 13.51 (8) [little bit faster] 11. Let's see "clean" O2 (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -O2): X 16.58 (6) C 14.14 (11) [much slower in console (11th place)] 12. And "clean" Os (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -Os): X 16.28 (2) C 13.11 (3, 4) [great! I didn't expect this] 13. Let's play with Os (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -Os -fomit-frame-pointer): X 16.49 (5) C 13.03 (2) [hmm, strange - faster in console and slower in X] 14. Go Os Go! (-mcpu=pentium-mmx -march=pentium-mmx -mmmx -Os -fomit-frame-pointer -falign-functions=4 -falign-jumps=4): X 16.31 (3) C 12.99 (1) [fastest in console! very close to first and second place in X; this is different result than Bill Kenworthy got (see http://article.gmane.org/gmane.linux.gentoo.user/50998)] Note that this test is specific to one task in one application. Effect can be different for whole system (see different effects of some options when application is running in X (system with many processes) and in console (minimum processes)). Machine specs: $ uname -rmip 2.4.20-gentoo-r7 i586 Pentium MMX GenuineIntel Kernel is compiled with preemptive multitasking. Processor: Pentium 166 MMX, RAM: 64MB Robert. -- Robert Cernansky E-mail: [EMAIL PROTECTED] Jabber: [EMAIL PROTECTED] -- [EMAIL PROTECTED] mailing list
