Date: Sun, 25 Feb 2007 21:47:44 -0500 From: Chuck Swiger <cswiger@mac.com> To: deeptech71@gmail.com Cc: freebsd-questions@freebsd.org Subject: Re: compiling always generates fast code? Message-ID: <45E24A50.6030405@mac.com> In-Reply-To: <45E218CC.7060902@gmail.com> References: <45E218CC.7060902@gmail.com>
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deeptech71@gmail.com wrote:
> Do you get processor-specific code when you do buildworld and
> buildkernel, particularly on a -RELEASE?
No, not unless you've configured the kernel Makefile and /etc/make.conf to
include processor-specific CFLAGS. See /usr/share/examples/etc/make.conf.
> Does building from ports always automatically optimize code (vs packages)?
Both ports and packages are optimized at the default level of "-O", unless you
set it otherwise. The kernel & world are known to be safe building using:
-O2 -fno-strict-aliasing
> Do I need to strip some files after the compilation (world, kernel,
> ports) to get the absolute maximum performance?
>
> Any other tips to speed up executables?
Sure, benchmark performance and make sure you run any self-testing routines
("make test" or "make check", usually) when you experiment with non-default
optimizations.
Pay attention to whether you obtain significant gains by using non-default
optimizations, because the answer generally varies in different situations and
on different CPU types.
--
-Chuck
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