AMD Sempron CPUTYPE & Co.

Andrew P. infofarmer at gmail.com
Fri Sep 23 12:44:17 PDT 2005


On 9/23/05, jason <jason at ec.rr.com> wrote:
> Andrew P. wrote:
>
> >On 9/22/05, jason <jason at ec.rr.com> wrote:
> >
> >
> >>Andrew P. wrote:
> >>
> >>
> >>
> >>>Hello!
> >>>
> >>>So I have a Sempron 2500+ CPU, one that supports
> >>>SSE3. What should I place in my /etc/make.conf? I use
> >>>ssh with X11Forward very often, so OpenSSL should
> >>>be compiled to be as fast as it can be on this CPU.
> >>>Here's a part of dmesg:
> >>>
> >>>CPU: AMD Sempron(tm) Processor 2500+
> >>>(1407.05-MHz 686-class CPU)
> >>>Origin = "AuthenticAMD"  Id = 0x20fc2  Stepping = 2
> >>>
> >>> Features=0x78bfbff<FPU,VME,DE,PSE,TSC,MSR,
> >>>PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,
> >>>PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2>
> >>> Features2=0x1<SSE3>
> >>> AMD Features=0xe2500800<SYSCALL,NX,MMX+,
> >>><b25>,LM,3DNow+,3DNow>
> >>>
> >>>I want to use SSE3, but I don't want to set CPUTYPE
> >>>to nocona, cause that way compilers won't ever use
> >>>AMD features. Is there a way to tell compilers to use
> >>>every feature I've got?
> >>>
> >>>
> >>>Thanks very much,
> >>>Andrew P.
> >>>_______________________________________________
> >>>freebsd-questions at freebsd.org mailing list
> >>>http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> >>>To unsubscribe, send any mail to "freebsd-questions-unsubscribe at freebsd.org"
> >>>
> >>>
> >>>
> >>>
> >>>
> >>man make.conf and man gcc
> >>
> >>You will be limited by the gcc version on FreeBSD.  You can use gcc 4
> >>for your apps, and all that SSE and 3DNow  stuff is not currently
> >>allowed in the kernel.
> >>
> >>I remember ready, maybe on slashdot, where a man did very little work to
> >>do a native port of ssh to native amd64 code and got a hugh speed
> >>boost.  Making sure you get a optimized version os ssh like what I
> >>described will make a much bigger difference than just adding amd64 as
> >>your cp type to make.conf.
> >>
> >>Jason
> >>
> >>
> >
> >I run FreeBSD/i386, not amd64.
> >
> >make.conf, gcc and cpp manpages tell you nothing about
> >the subj. I roamed mailing lists for a few hours and settled on
> >adding "-march=pentium4 -msse3" to CFLAGS and COPTFLAGS.
> >I didn't do any serious benchmarking, but the `top` output feels
> >like sshd got 2-3% performance boost. Will try to recompile
> >with "-mfpmath=sse" later.
> >
> >Also, I tried forwarding X11 over network without SSH, and
> >some things kept lagging. My guess is network connection
> >and my solution is a Gigabit switch; the funny thing is that
> >I have Gb NICs in most of my PCs, but I still use a 100Mb
> >switch.
> >
> >
> >
> Hmm, that sucks.  The K8 core in 32bit mode.  I have heard of native 32
> bit semprons, is that what you have?
>
> Well check this man page
> http://gcc.gnu.org/onlinedocs/gcc-3.4.4/gcc/i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options
>
> it will have everything, I hope, you need to know.
>

Native 32-bit mode? All AMD Athlon64/Sempron/Opteron CPUs
support 32-bit mode quite natively. As for Semprons - there are
some called "64-bit enabled". I have one of those.

Thanks very much for the link. I put some knobs into my
make.conf file - but it's not just that easy, no. Some apps
do not like the newer knobs like -msse3, so I have yet to
come up with a better solution than to edit make.conf
before each build.


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