Comment Re:16GB RAM and GCC optimization (Score -1, Flamebait) 357
I've been using Gentoo for about 10 years now. You really need to learn before opening your mouth. Please refer to Gentoo's GCC Optimization Guide. Especially pay VERY close attention to two very important parts:
1:
"In 3.x, -O3 has been shown to lead to marginally faster execution times over -O2, but this is no longer the case with gcc 4.x. Compiling all your packages with -O3 will result in larger binaries that require more memory, and will significantly increase the odds of compilation failure or unexpected program behavior (including errors). The downsides outweigh the benefits; remember the principle of diminishing returns. Using -O3 is not recommended for gcc 4.x."
(emphasis Gentoo's, not mine)
2:
"Some users boast about even better performance obtained by using -O4, -O9, and so on, but the reality is that -O levels higher than 3 have no effect. The compiler may accept CFLAGS like -O4, but it actually doesn't do anything with them. It only performs the optimizations for -O3, nothing more.
Need more proof? Examine the gcc source code:
Code Listing 3.1: -O source code
if (optimize >= 3)
{
flag_inline_functions = 1;
flag_unswitch_loops = 1;
flag_gcse_after_reload = 1;/* Allow even more virtual operators. */
set_param_value ("max-aliased-vops", 1000);
set_param_value ("avg-aliased-vops", 3);
}
As you can see, any value higher than 3 is treated as just -O3."
Read this stuff. It actually is kinda important...
M.
