From: Torbjorn Granlund <t...@gmplib.org> Date: Fri, 04 Jan 2013 15:17:11 +0100
> I expect them to add 3n/2 to 3n cycles, depending on the pipeline > characteristics. Each load can issue in 1 cycle, there is a 4 cycle latency, the loads will fully pipeline. Therefore the overhead is around 3n. > The Oracle manuals recommend that one loops around mpmul checking for > intermittent hardware failure, whatever that means. Parity errors on the register files, nothing that actually happens in practice. > Our current Karatsuba code (evaluating in 0, -1, oo) will suffer from > the forgotten subtraction instructions. Evaluating in 0, +1, oo might > be better... As I said in my other reply it depends upon how you need this subtract. If you need it for submul_1 or similar, that's not a problem. That only needs subcc+addxc which we have. If it's needed for sub_n, then yes that's a bit difficult. I was trying to figure out ways to fabricate the needed calculations using just subcc and addxc/addxcc but haven't come up with anything just yet. _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org http://gmplib.org/mailman/listinfo/gmp-devel
