Thread: Faster GPU-ECM with CGBN View Single Post
2021-09-09, 17:03   #89
SethTro

"Seth"
Apr 2019

2×191 Posts

Quote:
 Originally Posted by chris2be8 Just the higher arch one (sm_52). Sorry. PS. Does CGBN increase the maximum size of number that can be handled? I'd try it, but I'm tied up catching up with ECM work I delayed while I was getting ecm-cgbn working.
Yes! In cgbn_stage1.cu search for this line
/* NOTE: Custom kernel changes here

You can either add a new kernel or I recommend just changing cgbn_params_512

- typedef cgbn_params_t<4, 512> cgbn_params_512;
+ typedef cgbn_params_t<TPI_SEE_COMMENT_ABOVE, YOUR_BITS_HERE> cgbn_params_512; // My name is a lie

The absolute limit is 32,768 bits. I found that GPU/CPU performance decreases 3x from 1,024 bits to 16,384 bits then an additional 2x above 16,384 still something like 13x faster on my system but possible no longer competitive watt for watt. Read the nearby comment for a sense of how long it will take to compile.