[Discuss-gnuradio] SCC v. CCC filter performance

[David Carr]

Matt,

In an earlier post your mentioned that the CCC filter implementations
had been considerably improved.  Here are the results on my machine
(2.4GHz P4 no HT)

address@hidden tests $ ./benchmark_dotprod
   generic: taps:  256  input: 4e+07  cpu: 11.630  taps/sec:  8.805e+08
       SSE: taps:  256  input: 4e+07  cpu:  4.563  taps/sec:  2.244e+09
address@hidden tests $ ./benchmark_dotprod_ccc
   generic: taps:  256  input: 4e+07  cpu: 103.184  taps/sec:  9.924e+07
       SSE: taps:  256  input: 4e+07  cpu: 16.019  taps/sec:  6.393e+08
address@hidden tests $ ./benchmark_dotprod_ccf
   generic: taps:  256  input: 4e+07  cpu: 100.301  taps/sec:  1.021e+08
       SSE: taps:  256  input: 4e+07  cpu: 12.830  taps/sec:  7.981e+08
address@hidden tests $ ./benchmark_dotprod_fcc
   generic: taps:  256  input: 4e+07  cpu: 86.419  taps/sec:  1.185e+08
       SSE: taps:  256  input: 4e+07  cpu: 14.059  taps/sec:  7.284e+08
address@hidden tests $ ./benchmark_dotprod_fsf
   generic: taps:  256  input: 4e+07  cpu: 27.738  taps/sec:  3.692e+08
       SSE: taps:  256  input: 4e+07  cpu: 21.264  taps/sec:  4.816e+08
address@hidden tests $ ./benchmark_dotprod_scc
   generic: taps:  256  input: 4e+07  cpu: 94.179  taps/sec:  1.087e+08
       SSE: taps:  256  input: 4e+07  cpu: 31.658  taps/sec:  3.235e+08

The SSRP produces short input and I usually connect it to a frequency
xlating scf filter.  While I don't have a scf benchmark, it looks like
the the ccc filter is 2x faster than the scc filter in SSE mode.  If my
math is correct, a ccc filter requires more operations per tap than a
scc filter?!?  Could similar improvements be made in the sc* filters or
should I cast my incoming short data stream into a complex stream?

Thanks,
David Carr