Date: Sat, 10 Dec 2011 11:54:56 +0100 From: rank1seeker@gmail.com To: hackers@freebsd.org Subject: Re: CPUTYPE and friends, from 'make.conf' benchmark Message-ID: <20111210.105456.372.1@DOMY-PC> In-Reply-To: <CAGFTUwMEeGPtmJcMXLrCv12xQLXcGcWic5BdUvodiCjHSYAUqw@mail.gmail.com> References: <CAGFTUwMEeGPtmJcMXLrCv12xQLXcGcWic5BdUvodiCjHSYAUqw@mail.gmail.com>
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My home server was also built with 'native' and it's unixbench score = was:=0D=0A231.3 (24.6 min)=0D=0A=0D=0A# /bin/sh -c "gcc -v -x c -E = -mtune=3Dnative /dev/null -o /dev/null 2>&1 | grep mtune | sed -e = 's/.*mtune=3D//'"=0D=0Aathlon-4=0D=0A=0D=0AHere it didn't return = 'generic'=0D=0A=0D=0AJust out of curiosity, I've removed 'native' and = left only 'CPUTYPE?=3Dathlon-xp'=0D=0AAfter rebuild of OS, it's unixbench = score is now:=0D=0A319.8 (22.4 min)=0D=0A=0D=0AThat is a 38.26%, global = speed gain!=0D=0ANow I'm 100% sure, 'native' should always be = avoided!=0D=0A=0D=0A=0D=0A> It is acceptable to set CPUTYPE and to append = certain flags to CFLAGS=0D=0A> in make.conf, and CPUTYPE is used in many = ports for=0D=0A> architecture-dependent build options.=0D=0A=0D=0ADefault = CFLAGS are are '-O2 -pipe'=0D=0AWhich are recommended and proven to be = safe?=0D=0A=0D=0A=0D=0A> The use of CPUTYPE usually has a relatively = modest affect on general=0D=0A> benchmarks in the base system, because a = lot of code there is=0D=0A> intentionally generic, and is compiled with = an older toolchain using=0D=0A> conservative flags, so aggressive = optimizations that can take fuller=0D=0A> advantage of CPU extensions are = not used.=0D=0A=0D=0AI believe because OS stability, is a top = priority.=0D=0A=0D=0A> However, CPUTYPE can have a dramatic affect on = certain applications=0D=0A> when used with appropriate compiler flags = (-O3, etc.), particularly=0D=0A> those in some ports.=0D=0A=0D=0ASo, = CPUTYPE is mainly for boosting performance of ported apps.=0D=0ARegarding = compiler flags (-O3, etc.) I use them, only if port offers = them.=0D=0A=0D=0A> =0D=0A> b.=0D=0A> =0D=0A=0D=0ADomagoj Smol=E8i=E6
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