Date: Wed, 1 Jun 2011 14:46:22 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Adam Vande More <amvandemore@gmail.com> Cc: questions@freebsd.org Subject: Re: I486_CPU or I586_CPU in kernel config Message-ID: <alpine.BSF.2.00.1106011433070.19512@wonkity.com> In-Reply-To: <alpine.BSF.2.00.1105301708120.11485@wonkity.com> References: <alpine.BSF.2.00.1105300842550.9995@wonkity.com> <BANLkTikUwUp8AGKz9uGyjwMpD3H6D9oBFA@mail.gmail.com> <BANLkTikRggozSjXrGUhTJrzSNaM02jfZEQ@mail.gmail.com> <alpine.BSF.2.00.1105301708120.11485@wonkity.com>
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On Mon, 30 May 2011, Warren Block wrote: > On Mon, 30 May 2011, Adam Vande More wrote: > >> Perhaps this is the one you meant? >> >> http://lists.freebsd.org/pipermail/freebsd-questions/2009-January/190568.html > > That's the one! Thanks! > >> Actually the two threads touch on the same subject, and it seems removal of >> those options is still desirable on newer CPU's. > > sys/i386/i386/support.s is mentioned, but doesn't seem to have anything > explicitly specific for 586. There are some i686 entries. > > A test for cpu_class==CPUCLASS_586 in /sys/i386/isa/npx.c is mentioned in the > thread, but that check isn't in the current code. A little empirical testing: Times for buildworld after a fresh reboot, /usr/obj/usr deleted, GENERIC included, running ccache: default (486/586 included) 9:05.84 nocpu I486, nocpu I586_CPU 9.27.88 nocpu I486_CPU 8.53.86 So maybe a 6% increase by removing 486 but leaving 586... These were not rigorous benchmarks, it might just be measurement noise.
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