Finally found a use for "/"...
The past few days I've decided to rent some pretty significant firepower for p2pool. Although it hasn't helped us solve any blocks, it has certainly given me some interesting data points to consider. Thought I'd share with the class
Normally I've got 9 S3s pointing to my p2pool nodes. The past few months, I've had a couple redirected to OgNasty's node for a test, but they're all still on p2pool in some fashion or other.
The past few days I've rented anywhere from 200 - 400 TH/s of miners. I've pointed that hash to my node and have tried a few different combinations of settings to see what happened.
My S3s I have configured like this: "ADDRESS+500". They have remained constant with that setting.
The rentals I've done a bunch of stuff to see what effect it would have on my S3s. Here's what I've found:
ADDRESS/4096 (or any /xxx where xxx is less than share difficulty): the node will ALWAYS set the share difficulty for this worker to be the standard p2pool share difficulty. So, if p2pool has a difficulty of 10,000,000, that's what the difficulty will be for this worker.
ADDRESS: Not using the "/" sets the difficulty for this worker based upon the node's hash rate. What I've found is that it tries to get the time to find a share around 30 minutes.
ADDRESS/50000000 (or any value higher than share difficulty): As you'd expect, if you provide a value higher than p2pool's difficulty, the node sets that difficulty for your worker.
So...
If you're a miner and you're on a node where the node's total hash rate is significant, and you're not the source of that high hash rate, you should use some value for "/". Why? Because that miner with the high hash rate might be relying upon the node to set the difficulty, which will hurt you in terms of time to share.
If you're the miner who's got the extremely high hash rate, do the rest of the miners on that node a favor and set your share difficulty high enough to ensure you're not submitting shares more often than every 30 minutes or so. It's pretty easy to calculate this value:
Difficulty * 2^32 / hash rate = time to share
Therefore, to get the difficulty if you've got 200TH/s:
Difficulty = 1800 * 200000000000 / 2^32
So, if you've got 200TH/s, you should set your difficulty to 83819031.
Anyway, food for thought while I'm sitting here at the airport waiting for my delayed flight to take off
