Quote from: ssateneth on August 09, 2011, 05:40:16 PM

Quote from: BOARBEAR on August 09, 2011, 05:06:12 PM

I found that VECTER4 option does not work for version 2.2

Same. Using VECTORS4 drops my hash rate from 385 to 310 on my 5870. Using VECTORS WORKSIZE=128 brings it back up to about 380.

This is probably because of the increased GPR usage of the VECTORS4 code. According to KernelAnalyzer VECTORS4 uses 2707 ALU OPS and 33 GPRs. This is compared with VECTORS which is 1355 ALU OPS and only 23 GPRs. Theoretically VECTORS4 would be faster, since it tests twice the number of nonces using 3 fewer ALU OPS than 2 executions of VECTORS. However, if the GPU runs out of GPRs then this limits the number of threads that can be running at once, which is what causes the performance drop.

(Above ALU OPS and GPR numbers are for Cypress, AKA 58xx)

VECTORS4 might be faster for 69xx users though, when combined with a smaller WORKSIZE.

EDIT: Just looked at the 2.1 version and it uses even more GPRs with VECTORS4 than 2.2 does. (35 GPRs, 1358 ALU OPS) I'm not quite sure how it can be faster than 2.2.