Author: Vincent Diepeveen
Date: 09:17:41 02/17/05
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On February 16, 2005 at 18:43:20, Frank Phillips wrote: here is what i do with diep at x86-64 which speeds up quite some : i take care that not a single file is there of the profile info and remove all objects. first Run : CFLAGS = -fprofile-generate -O3 -march=k8 -mtune=k8 -DUNIXPII then i start diep and run it for an hour analysing at openings position. then i quit diep. do this a single time. don't run it 2 times. just a SINGLE time otherwise the thing might get confused again. GPL programmers :) then secondly delete all object files and recompile with: CFLAGS = -fprofile-use -O3 -march=k8 -mtune=k8 -DUNIXPII The above works for diep. # -fif-conversion -frerun-loop-opt <== slows down diep a bit >On February 16, 2005 at 17:46:23, Vincent Diepeveen wrote: > >>On February 16, 2005 at 13:09:14, Frank Phillips wrote: >> >>>Has anybody got any experience with g++ 3.4 for amd64 (x86_64) - for Linux? >>> >>>I have been using the profile generated optimisation option, but the code it >>>produces is no faster then with simple -O3. >>> >>>I simply compile with -fprofile-generate >>>then run, >>>then recompile with -fprofile-use. >>> >>>The relevant *.gcno, *.gcda files are produced. Must be doing something >>>wrong..... >>> >>>Frank >> >>First of all get the LATEST version of gcc. thats 3.4.3 now. and if when i post >>3.4.4 is released get that one. like bob my experience is that the PGO in gcc is >>pretty buggy. >> >>icc is however such a bad optimizing compiler that gcc is far faster for diep. i >>guess icc is better bugfixed for 64 bits code as that mattered for specint2000, >>guess why :) >> >>Anyway gcc isn't that great in 64 bits perhaps, but it's scheduling better for >>opteron than icc is, which for diep is more important. icc of course is only >>good for intel hardware when your program hasn't been in specint yet. >> >>main idea is. delete all your files except source files. >> >>THEN run the fprofile generate single cpu. >> >>then delete all object files >> >>then run the profile use. >> >>never use intel c++. they will do anything to slow you down at AMD hardware. >> >>Vincent > >Thanks, I do remove object files before recompiling after the profile run. > >What is confusing, is that I get no speed up at all over plain -O3, which made >me suspect I must be doing something wrong. (Although all I have done is change >fprofile-arcs / fprofile-branch-probabilites to fprofile-generate / fprofile-use > in the makefile and the latter pair did have an effect in gcc3.3 - I think.). > >Frank > >BTW icc gave me 20-30% speed up in 32 bit mode over gcc. My program is an unholy >mixture of bitboards and array look-up for move generation. The 64 bit amd and >slower gcc slightly overcompensates for the loss of the 32bit Intel compiler.
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