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author | bde <bde@FreeBSD.org> | 2008-03-30 18:07:12 +0000 |
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committer | bde <bde@FreeBSD.org> | 2008-03-30 18:07:12 +0000 |
commit | 2916ad3e28c0f7fea67ffe9b7af7f51b6e3aaaf0 (patch) | |
tree | 94cad26c2877839b64fe3a8e8a6b961683a86d57 /sys/netncp | |
parent | b06e3a074e790b19403a03d0155466a343805194 (diff) | |
download | FreeBSD-src-2916ad3e28c0f7fea67ffe9b7af7f51b6e3aaaf0.zip FreeBSD-src-2916ad3e28c0f7fea67ffe9b7af7f51b6e3aaaf0.tar.gz |
Use fabs[f]() instead of bit fiddling for setting absolute values.
This makes little difference in float precision, but in double
precision gives a speedup of about 30% on amd64 (A64 CPU) and i386
(A64). This depends on fabs[f]() being inline and efficient. The
bit fiddling (or any use of SET_HIGH_WORD(), which libm does too
much because it was best on old 32-bit machines) always causes
packing overheads and sometimes causes stalls in the packing, since
it operates on only part of a variable in the double precision case.
It apparently did cause stalls in a critical path here.
Diffstat (limited to 'sys/netncp')
0 files changed, 0 insertions, 0 deletions