I have more than 100 instances of VPS!
Then you should probably experiment with settings if you believe that the default settings might not be optimal.
For example, you might adjust one setting for half of these instances and run the whole lot for some days to see whether it makes a difference.
If the new setting is better than the old one, use it for the other half and either adjust another setting, or adjust the same setting a little more in the same direction.
Sort of running a genetic optimization algorithm manually.
If you don't want to go through the hassle, you should probably just take the default settings. They are default because the authors thought that they yield best results in normal cases.
Onkel Paul
Do you know what PPS is the best to get lucky because I could ramp up the cores to get better results? Like if the PPS is more than 1k then I can have all of my instances average above that number instead of having less with higher PPS. Is this the best strategy?
Searching for Cunninghan chains (Primecoin/Datacoin mining) involves the following steps:[Double SHA-256 for the block/block header hashing (CPUs are dreadfully slow for this task)
Modular reduction per sieving prime (using the double SHA-256 result from the block header hash)
Modular multiplicative inverse per sieving prime (using the result from the previous step - we need a starting point for the sieving prime)
Bit array masking or call it sieving (using an array of 32-bit integers that should fit in your CPU's L1 data cache: AMD 64KB, Intel 32KB)
Modular exponentiation on the CPU - sliding window (GMP: Karatsuba + Montgomery reduction)
Now remember that
we are searching for chains and not for primes, therefore Primes Per Second (PPS) means absolutely nothing by itself.
Your goal is to actually reduce the number of PPS while increasing your number of probable chains per second (CPS). During your sieving/bit masking process, what you are actually doing is eliminating all of the composite numbers/false chains that would never meet the requirements for your current difficulty.
Therefore, the theoretical ratio for difficulty 10 is: 10PPS / 1CPSSo where does tuning come in? First find out if you are running on AMD processors (K10), if so, then double the cache settings and recompile. You may also have to lower your sieve extensions because the AMD processors typically have 64KB/64KB for L1 instruction/data caches. If you are running on Intel processors then Mikaelh's code should work well as is.
Tuning involves finding the cutoff point where sieving is no longer as effective as performing modular exponentiation to eliminate false chains per unit of time.