Did I understand correctly: we need to recalculate the global variable "s" after each submitted share?
Suppose there is a large pool which handles a few TH/s (a hundreds shares per second). What if operator will recalculate 's' only on each 100th share? How it will affect miners?
The calculations are lightning fast, updating s hundreds of times per second shouldn't be a problem. Well, doing it locally in your front end system and then storing it/updating it every so often. I wouldn't want to do hundreds of sql updates per second just to update the value of s. Update it on every share and store it every 100 (or some number) of shares in your database. If you have 100 shares/sec and store it every 500-1000 shares, then if the front end crashes/etc you only lose 5-10 seconds of data which may not be all that bad. Or do it every 100 shares. 1 sql query per second is no issue.
Thanks, but you answered a different question =) I agree that 100-1000 multiplications per sec is not a problem. But I'd like to know if recalculating 's' on every
i'th step is a reasonable optimization for large pools?
Not really.
I'm still not sure what is the motivation, "recalculating" s is more or less one multiplication, it's completely trivial. Storing it in the db might be more expensive, but aren't you storing each share in the db anyway?
Shift-PPLNS and shift-DGM are more friendly for scalability.
