[mythtv] [patch] mythtv-HOWTO-5.html - compiling for different
Daniel Thor Kristjansson
danielk at mrl.nyu.edu
Tue Dec 28 23:12:56 UTC 2004
On Tue, 28 Dec 2004, Isaac Richards wrote:
]> This patch removes the -mfpmath=sse performance recommendation, but
]> keeps the additional archs, such as the winchip, the updated C3 info,
]> and other Intel and AMD processors.
]Have you profiled on each of those processors to see if setting the arch
]actually creates faster code? I've seen -march=athlon-xp create 50% slower
]code than -march=pentiumpro with a recent gcc..
No, I only have Intel processors at my disposal. Compiling for pentium4
gives me a 30% speed boost. For the rest, I based this on the gcc
manual. I've heard rumors about xp optimization being broken, but I
can't verify this myself.
I made this patch to the documentation because someone was having
problems compiling mmx_gcc.cpp because they were targeting the
pentiumpro, which did not support MMX. The compiler, rightly, did
not generate the MMX code.
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