[1500 TH] p2pool: Decentralized, DoS-resistant, Hop-Proof pool

[TheHarbinger]

What is going on?  It seems very strange that we don't solve a block all day and then solve three blocks in a row!?

Variance.  It explains all.

[ChanceCoats123]

To take a break from the serious conversations going on in this thread right now...


I just want you to know, I'm the one who found the block that broke the 23h 49m without a block drought.  No thanks necessary. But tips are, pay me bitches! 

Lololol

[kano]

To take a break from the serious conversations going on in this thread right now...


I just want you to know, I'm the one who found the block that broke the 23h 49m without a block drought.  No thanks necessary. But tips are, pay me bitches! 

P2Pool gave you a tip for finding it
Not sure why more pools don't do that ...

[jothan]

I posted a pseudo-spec on what would be required to mine on P2Pool with BFL hardware, thought this was relevant.

https://bitcointalk.org/index.php?topic=78540

Thanks !

[Tittiez]

Its nice to see luck increasing a little.

[echris1]

Its nice to see luck increasing a little.

No, ah!  Shouldn't have said anything. 

Heh, just kidding.  Luck does seem to be getting a bit better, plus I just found a block (178015) which always makes me feel lucky =)  I think that is four blocks ever found for me, unless I missed one somewhere. 

[Tittiez]

Its nice to see luck increasing a little.

No, ah!  Shouldn't have said anything. 

Ah shit oops.

[echris1]

So I checked my namecoin balance recently (something I tend to forget to do)  and noticed some coins.  So I dug through the log file and came up with this:


$grep submittal ~/p2pool/data/bitcoin/log
2012-04-27 16:34:07.646242 > Merged block submittal result: False Expected: True
2012-04-29 09:16:43.527938 Merged block submittal result: True
2012-04-30 20:00:57.030804 Merged block submittal result: True

Is that first one a namecoin block that was orphaned or invalid somehow? I'm guessing its not orphan, since as I understand it you wouldn't know about that right at submittal.  I have only ever found a few namecoin blocks so I'm not sure what the log usually looks like.  Just curious really, anyone know?

[ChanceCoats123]

Its nice to see luck increasing a little.

Oh god, all is lost! I ruined it last time and now it's happened again... New P2pool thread rule: NO TALKING ABOUT THE LUCK!

[Aseras]

Its nice to see luck increasing a little.

Oh god, all is lost! I ruined it last time and now it's happened again... New P2pool thread rule: NO TALKING ABOUT THE LUCK!

yeah this morning it was terrible. 5m blocks. just plain suck. lol

[twmz]

There have been on and off discussions of if the p2pool.info luck calculations are somehow wrong (i.e. too low) because of some error in the estimated hashrate, etc.

I did an experiment with independent data to see how it compared and here are the results.

Instead of looking at anything from p2pool, I looked at my payments over the past 30 days.  My personal p2pool hashrate has been unchanged during the past 30 days and I have a detailed record of every share I have found, so I am certain what my hashrate was during that duration.  Note, I did happen to be the block finder for one of our blocks in the past 30 days, and so I did even receive a bonus payment to counter balance all the other blocks where I didn't receive the bonus payment, so that effect is mostly washed out.

Taking the difficulty changes into account, I calculated what my expected payment should have been over the past 30 days given my hashrate.  I compared that with what I was actually paid.  Over the past 30 days, I received 78% of amount that I was expected to have received given my hashrate.  The luck calculation from p2pool.info (which is based on average pool hashrate and blocks found) calculates that the past 30 day luck is 77%.

77% global luck vs 78% personal luck.

That makes me pretty comfortable that the p2pool.info luck calculation approach is not fundamentally broken and off by 10% or something. 

If anyone else sees a different pattern in their own personal payouts, that would be interesting.

[DeathAndTaxes]

Thanks for doing that twmz.  Sadly that isn't what I wanted to hear.

While 80% over 90 days is plausible looking beyond 90 days the likelihood of such a low % becoming increasingly unlikely.

Since inception the pool has found 372 blocks.  Stats for the first block are unknown so we will exclude that.  

# Blocks: 371
Estimated shares in blocks:  619,152,160
Expected shares in blocks:  547,529,631
Lifetime Luck 87.9%
Shares per block relative to expected.  1.13x

I calculate
Actual # of blocks: 371
Expected # of blocks: 422

Mining is a possion distribution.
The odds of having 371 or less events when 422 are expected is 0.71%
http://www.sbrforum.com/betting-tools/poisson-calculator/

There is only a 0.71% chance we are just facing bad luck and a 99.29% chance something is resulting in less blocks found.

I am certain that "something" isn't malicious intent by developer however something is causing us to find less blocks than expected.

A number of theories:
a) some nodes are accidentally not submitting blocks.
b) something in the code is causing valid blocks to not be detected.
c) someone with ~40GH/s is intentionally withholding blocks to damage the network.
d) the stats are inaccurate and twmz observation is coincidental (I don't believe it just included it for completeness)
e) we are finding more blocks but they are being orphaned at a higher rate (>10%) and those orphans aren't being seen by p2pool.info node.
f) there is some bias in SHA-256 hash (unlikely but not impossible) such that low nonce values are less likely to find blocks that higher ones, due to LP p2pool searches more low nonce values
f) someone has found a method to "cheat" the p2pool reward algorithm

Note not all of these are equally likely I am just kinda brainstorming and putting down any possibility no matter how remote.

A couple suggestions:
a) found blocks should be forwarded to all nodes regardless of their staleness (this will aid in troubleshooting if nothing else)
b) some mechanism of recording the exact # of shares per round would be useful.

That being said I can no longer afford to take a 20% haircut on revenue so I will be temporarily leaving p2pool.

On edit:  I will leave one rig on p2pool using new address and attempt to gather detailed stats on shares vs payout.

[twmz]

A number of theories:
e) we are finding more blocks but they are being orphaned at a higher rate (>10%) and those orphans aren't being seen by p2pool.info node.

It's certainly possible, but I wanted to add that p2pool.info now also asks blockchain.info for a list of all blocks (including orphaned blocks) that include the p2pool donation address.  I trust that blockchain.info is much more likely to have seen all orphaned blocks (excluding the recent downtime) given that they connect to almost every publicly accessible node.  I think the likelyhood of unnoticed  orphaned blocks is very low at this point.

A couple suggestions:
a) found blocks should be forwarded to all nodes regardless of their staleness (this will aid in troubleshooting)

I believe forrest just commited this change to the git tree last night.

[kano]

Another reduction will come from the fact that some % of miners won't have 'submit stale' enabled in whatever they mine with.
No idea how big or small that is, but, of course, that relates directly to what I was mentioning before.

[Red Emerald]

Another reduction will come from the fact that some % of miners won't have 'submit stale' enabled in whatever they mine with.
No idea how big or small that is, but, of course, that relates directly to what I was mentioning before.

Also, when comparing actual payout to expected, make sure not to forget the author donation.  0.5% isn't much, but it still can matter.

[mav]

I have a theory that hashrate is being reported incorrectly by p2pool and is skewing the luck calculation. I realise that luck is a comparison of hashes by shares vs hashes in blocks and may not be related to the reported GH/s value, but I thought the numbers below were too compelling not to mention.

My phoenix thread says my hashrate per gpu core is always 380-390 MH/s. It's very consistent. I have 12 cores so that makes for a hashrate range between 4.56 GH/s and 4.68 GH/s

In my p2pool thread I see my total local hashrate usually around 4.8 to 5 GH/s and often up to 5.1 GH/s

Taking the average phoenix hashrate vs the average p2pool hashrate and the result is about 4.62 / 4.9 = 0.94

The most compelling part of all is that I recently switched to ozcoin for a while and they also report my hashrate at around 4.6 GH/s - the reported value by p2pool is never that low.

[kano]

Actually ... the luck calculation should be based on shares per block ...
Which I presume it is anyway.

[ChanceCoats123]

I have a theory that hashrate is being reported incorrectly by p2pool and is skewing the luck calculation. I realise that luck is a comparison of hashes by shares vs hashes in blocks and may not be related to the reported GH/s value, but I thought the numbers below were too compelling not to mention.

My phoenix thread says my hashrate per gpu core is always 380-390 MH/s. It's very consistent. I have 12 cores so that makes for a hashrate range between 4.56 GH/s and 4.68 GH/s

In my p2pool thread I see my total local hashrate usually around 4.8 to 5 GH/s and often up to 5.1 GH/s

Taking the average phoenix hashrate vs the average p2pool hashrate and the result is about 4.62 / 4.9 = 0.94

The most compelling part of all is that I recently switched to ozcoin for a while and they also report my hashrate at around 4.6 GH/s - the reported value by p2pool is never that low.

I had mentioned this before, and I believe someonw responded saying that the reported hashrate from p2pool.info is based upon the shares you have per the time, so you might just been lucky in your share finding which raised the "hashrate" that p2pool saw.

[mav]

I had mentioned this before, and I believe someonw responded saying that the reported hashrate from p2pool.info is based upon the shares you have per the time, so you might just been lucky in your share finding which raised the "hashrate" that p2pool saw.

But to be lucky all the time makes it seem like it's an incorrect value and not due to luck. I never saw my p2pool hashrate reflect my phoenix hashrate.

Is the hashrate used in the calculation of luck or is it just 'an indicator that things are happening' for the user?

[ChanceCoats123]

There is where it's different for me and you.

My actual is 1250mhash. P2pool.info will give me a range (depending upon when I check) between 1100 and 1500. So that makes sense for me. How long have you been mining?