On Fri, Oct 24, 2008 at 08:19:49AM -0700, Philip Balister wrote: > On Fri, Oct 24, 2008 at 6:27 AM, Eric Blossom <[EMAIL PROTECTED]> wrote:
> >> [EMAIL > >> PROTECTED]:/home/balister/oe/tmp/work/armv7a-angstrom-linux-gnueabi/gnuradio-3.1.3+svnr9809-r4.1/trunk/gnuradio-core/src/tests# > >> ./benchmark_dotprod_fff > >> generic: taps: 256 input: 4e+07 cpu: 968.586 taps/sec: 1.057e+07 > >> cortex_a8: taps: 256 input: 4e+07 cpu: 45.703 taps/sec: 2.241e+08 > >> > >> Philip > > > > Cool! > > > > The good news / bad news is that the spread is worse than on the P4! > > > > Is there a way to get the compiler to use the NEON instruction set in > > scalar mode? E.g., something like -mfpmath=sse on x86? Maybe -mfp=vfp? > > Are you providing the -mcpu=cortex-a8 gcc option? > > The Cortex-A8 numbers use assembler to unroll the inner loop 8 times. > I think this code can get better. I'll have to double check the flags, > but I do not think gcc does a good job generating code for the > vfp/NEON unit. (We are happy gcc can generate anything supporting NEON > and not crash ...) > > Remember, this is clocked at 600 MHz and consumes about 1 Watt. Understood. I'm trying to keep you out of the assembly business. The fact that your assembly code is 20 time faster is scary. That's why I was asking about compiler flags. I suspect that you're not telling gcc enough about the machine. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
