On 23 October 2013 16:27, Fredrik Johansson <fredrik.johans...@gmail.com>wrote:
> On Wed, Oct 23, 2013 at 4:17 PM, Bill Hart <goodwillh...@googlemail.com> > wrote: > > I have made a number of speedups to the precomputed inverse code I > announced > > earlier, and removed two unneeeded functions. It is now up to 20% faster > > than ordinary 2n x n division for n = 1 limb and from n = 3-15 limbs and > up > > to 2.2 times as fast above n = 120 limbs. > > So it's slower for n = 2 limbs? Could you hardcode this case? > Yeah, you could. But it wouldn't make much difference. I tried various things, but they always either didn't improve things, or made it slower. > > > There's nothing more I can do for it now. The gaps that remain are > essential > > gaps, due to the raw speed of the division code in the mpir trunk (the > code > > in mpir-2.6.0 is substantially slower). > > Seems like a pretty good improvement, even if there is a gap! > > > Unfortunately, in those gaps, the ordinary division code is up to 20% > faster > > than using a precomputed inverse. We could eventually close the gaps by > > rewriting mullow and mulhigh in mpir, but this is a lot of work, > including > > lots of assembly code and much careful thought about algorithms. > > Assembly optimised basecase mullow and mulhigh would be very useful > for many other things too. Few people have the skills to do this, > though, and you are probably right to prioritise other things... > Yep. > > > As it is, it is possible to switch on mpir's mullow code for one of the > > multiplications and it slows it down, again due to the raw speed of > mpir's > > ordinary multiplication code. > > Fredrik > > -- > > --- > You received this message because you are subscribed to the Google Groups > "flint-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to flint-devel+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "mpir-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to mpir-devel+unsubscr...@googlegroups.com. To post to this group, send email to mpir-devel@googlegroups.com. Visit this group at http://groups.google.com/group/mpir-devel. For more options, visit https://groups.google.com/groups/opt_out.
