Author: Matthew Hull
Date: 10:56:51 02/17/05
Go up one level in this thread
On February 17, 2005 at 12:17:41, Vincent Diepeveen wrote: >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 :) I guess none of that endgame code will ever get "profiled". Should you not run a variety of positions for the best profile? > >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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