While PPLNS is a well-understood payout system, it has itw own set of flaws, mainly high variance. Even at 8xD. (And counting which shares will have been paid at least once is nonsense, because that's equivalent to merely 12.5% PPS payout.) I dislike variance, and that's why I was at Eligius until things started to go bad (which I predicted months ago, but nobody would listen). I'm very willing to pay a 1-3% cut for true PPS payouts, and also accept modeare payout delays if the pool has bad luck. What I don't accept is share-based variance.
Another problem is that current EC credit will likely go unpaid to a large percentage in the end, which basically screws Eligius' most loyal miners!
(I'm personally mostly unaffected by this though, I've realized what was going to happen early enough.)
Sure, the current situation doesn't look good, and we need a change to fix that. The root cause of all this trouble is that for various reasons (orphan blocks, possibly withholders, ...) a true 100% PPS payout isn't sustainable in the long run by definition, but Eligius' non-equalized SMPPS payout model tries to pay each share 100%, regardless of what is feasible. If it can't, it will start to neglect more recent shares at the benefit of less recent ones, which leads us to where we are today.
So which payout level is sustainable in the long run? 95%? 98%? 99.5%? This depends on a lot of factors, and only time can tell.
What we need is a payout system that takes this fact into account.
I can think of two possible models:
- 95%-CPPSEB
Assuming we're certain that 95% PPS payout is sustainable in the long run, one option would be a 95% Capped Pay Per Share with Equalized Backpay system.
This basically means that, if the round was sufficiently short, each share of that round will be paid 95% PPS immediately. If the round was longer, it might be paid less. If the round was shorter, the excess credit is used to increase the PPS percentage of older shares (the ones that were paid the least).
This increases the chance of immediate 95% payouts for active miners, while ensuring that after some time all shares will have been paid almost equally much, however much is feasible in the long run (this dynamically adjusts itself).
Old EC from the current system could be carried over. If this route is taken, new shares would basically get a 5% fee at first, which is used to pay off old EC up to 95%. Once that point is reached, the payout level of all shares will slowly be increased to whatever is feasible.
See this link for more details on CPPS-based reward systems. - ESMPPS(AM)
Equalized Shared Maximum Pay Per Share is a system that basically works like Eligius' current reward system, just that it prefers the least-paid shares instead of the oldest ones. It will thus first pay the shares of the current round until they have been paid as much as the least paid previous shares. Then the remaining block reward will be used to increase the payout percentage of the least paid shares (including the shares from the current round).
This will show similar dips to CPPS* or PPLNS (just that for the latter they wouldn't be brought up to speed later) during long rounds, much better than with SMPPS in EC mode. So even if our luck would be down to 50% for a month, all shares would be paid about 50% PPS, and as soon as luck gets better, those shares will be backpaid by more recent higher-luck blocks. In the end this should end up paying about >98% PPS (whatever is sustainable, dynamically adjusting) to all shares after a while. Recent shares might see slight temporary dips, but not worse than with PPLNS, which doesn't even fill those dips later.
Even though this should not be necessary with an ESMPPS system, one could extend it to prefer old shares of currently active miners to keep people loyal. It would just use 90% of the block reward to pay shares of currently active miners (considering at most equally many old shares of a miner as he has mined in the current round, like it was proposed for Ra), up to a payout level of 100% PPS. The remaining 10% would be distributed across all old shares to eventually pay out all EC if luck permits. If not all of the 90% can be allocated to active miners, the remainder will go towards all shares as well.
Old EC from the current system could be carried over in two ways:- Consider every old share at its current payout state. This means that the system will try to reach equal payout levels on all shares, independent of when they were found (before/after the switch to the new model).
- Consider every old user/address at its current payout state. This means that the system will at the beginning prefer users that have been hit particularly badly by the current "EC mode sesion". Old users which have been paid an average of 98% PPS during their whole "eligius career" wouldn't be paid any of their EC until all users which had a worse "career" have been brought up to speed. I consider this approach more fair, and it will get the PPS percentage for newly mined shares into the 90+% area much faster than the alternative above.
See this link for more details on ESMPPS.
One additional advantage of these models is than (unless the AM addition is applied, which I don't consider necessary), these models are ready for a situation where transaction fees become predominant compared to the block reward, as it allows for >100% PPS payouts if transaction fees are included in the rewards, and luck + fees allow for >100% PPS.
Sure, if the switch to one of these models would have been performed much earlier, they would recover from the current situation much easier, but I don't think it is too late yet.
I simulated the ESMPPS model like a year ago when I was cooperating with another pool owner on finding a good reward system. The results looked pretty good. Sadly the pool it was invented for didn't really take off and never had more than like a dozen gigahashes, before it was finally shut down. I'm fairly certain that the reward system wasn't to blame though.
I demand that, before a switch to PPLNS is performed, these two models will at least be simulated and analyzed.
Feel free to contact me with any questions about these two proposed systems, preferably in #eligius on irc.freenode.net.
