Peercoin block time is not 10 minutes


#1

Everywhere in the Peercoin docs is written that Peercoin generates a block every 10 minutes, but it is a mistake, because considering PoS and PoW blocks Peercoin must generate a block every 8.57 minutes on average. In fact, last month, the Peercoin network generated a block every 7.78 minutes on average, and last year, every 8.23 minutes on average.

So, why does this mistake exist so long in the Peercoin docs?


#2

With difficulty changes and stochastic probability, it should be expected that average block time does not equal target block time. That said, I agree that block time in docs should be more explicitly spelled out.

I made a pull request for you:

If you see it pop up elsewhere, maybe we can try to use this thread to coordinate a campaign to disseminate this knowledge.


#3

there are 2 loops at play. The blockspace(is this a word?) for POS is set to 10 minutes, while the space set for POW varies up to 2 hours(need verified). So yeah, the avg in total can be lower than 10 minutes, thats correct.


#4

It’s spelled out in the same way that Bitcoin’s is spelled out. Difficulty is based on a SMA that constantly adjusts over time which gives you a target time of 10 minutes.


#5

There are two difficulties. One is PoS, which adjusts to aim for a PoS block every 10 minutes. The other is a PoW difficulty, which adjusts to aim for a PoW block every 60 minutes. The result is a block, on average, every 8.57 minutes. This number is what we should use when calculating max txns/second, giving us 8 tps instead of bitcoin’s 7 tps.


#6

I did a quick search and I encounted a list of POW block times: So it varies:

0 pos blocks in between: pow target = 20 min
1 pos blocks in between: pow target = 30 min
2 pos blocks in between: pow target = 40 min
3 pos blocks in between: pow target = 50 min
4 pos blocks in between: pow target = 60 min
5 pos blocks in between: pow target = 70 min
6 pos blocks in between: pow target = 80 min
7 pos blocks in between: pow target = 90 min
8 pos blocks in between: pow target = 100 min
9 pos blocks in between: pow target = 110 min
10+ pos blocks in between: pow target = 120 min


#7

We can all agree on PoS block spacing, for sure:

So the question is about PoW block spacing. I can’t find an equivalent declaration for PoW block spacing, so I’m open to the possibility that we adjust our PoW target based on number of PoS blocks. @thehuntergames can you link where you got this info?

Edit:


#8

here the post I made back in 2014. Ratio of PoW blocks versus PoS blocks
code might have been changed since then( i doubed it tho)


#9

So all told, it is quite complicated and may even not be an equilibrium system. The ratio seems to be pretty close to the 1:6 PoW:PoS per hour that I used to make the 8 tps statement, so I still think we should aim to keep that in the table. However, how to explain this in a succinct way in the docs and abroad is quite a heafty task.

It is clear to me that the average block time will be less than 10 minutes, especially as PoW difficulty continues upward as we can expect it to. Thank you for your help elucidating this, we should add this information in as concise a form as possible to the website.


#10

Please review before I PR this: