Author: Andreas Guettinger
Date: 18:42:36 12/05/03
Here the bitscan a friend of me made on his G5 1.8 Ghz:
Here is the output compiled with gcc -O3 on a single-G5/1.8:
magic bitscan 2980130816 5.320
magic bitscan 2980130816 5.130
magic bitscan 2980130816 5.150
magic bitscan 2980130816 5.150
------------------------------
table 16 2980130816 5.170
table 16 2980130816 5.480
table 16 2980130816 5.150
table 16 2980130816 4.870
------------------------------
gerd 2980130816 4.590
gerd 2980130816 4.550
gerd 2980130816 4.540
gerd 2980130816 4.570
------------------------------
eugene 2980130816 6.740
eugene 2980130816 6.850
eugene 2980130816 6.650
eugene 2980130816 6.730
------------------------------
eugene2 2980130816 5.030
eugene2 2980130816 5.120
eugene2 2980130816 5.150
eugene2 2980130816 5.370
It gets significantly faster when compiled with -fast (normally the difference
is not that big, these algorithms seem to be very 64-bit friendly).
The -fast switch allows the compiler to use G5-specific instructions like
64-bit registers.
magic bitscan 2980130816 2.600
magic bitscan 2980130816 2.340
magic bitscan 2980130816 2.360
magic bitscan 2980130816 2.360
------------------------------
table 16 2980130816 4.650
table 16 2980130816 4.660
table 16 2980130816 4.630
table 16 2980130816 4.670
------------------------------
gerd 2980130816 2.440
gerd 2980130816 2.440
gerd 2980130816 2.450
gerd 2980130816 2.450
------------------------------
eugene 2980130816 6.560
eugene 2980130816 6.610
eugene 2980130816 6.590
eugene 2980130816 6.580
------------------------------
eugene2 2980130816 3.280
eugene2 2980130816 3.280
eugene2 2980130816 3.290
eugene2 2980130816 3.270
For comparision the -O3 executable on a dual G4/1.0:
magic bitscan 2980130816 10.970
magic bitscan 2980130816 10.960
magic bitscan 2980130816 10.960
magic bitscan 2980130816 10.970
------------------------------
table 16 2980130816 7.250
table 16 2980130816 7.770
table 16 2980130816 7.110
table 16 2980130816 7.410
------------------------------
gerd 2980130816 12.260
gerd 2980130816 12.260
gerd 2980130816 12.250
gerd 2980130816 12.260
------------------------------
eugene 2980130816 12.420
eugene 2980130816 12.350
eugene 2980130816 12.320
eugene 2980130816 12.280
------------------------------
eugene2 2980130816 8.640
eugene2 2980130816 8.620
eugene2 2980130816 8.630
eugene2 2980130816 8.920
regards
Andy
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