Proof-of-work difficulty increasing

[Gavin Andresen]

How about in the options menu you can turn it off or on, and specify an interval in minutes for how often it should display?

I say keep it simple; more choices isn't always better, it just makes it overwhelming and confusing for most users.

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[satoshi]

Agree.  Certainly too trivial to clutter the user's attention with.

I changed it to every 30 minutes.

If I increased it to every 10 minutes, it would still be a small enough presence in the log file.  Question is whether that would be more output than the user wants when they grep.

[laszlo]

"difficulty" : 45.38582234101263

It jumped from 23 in a couple days.  I think this pretty much puts an end to generating a block a day with a personal computer.. but you can still get lucky.  Now you'll need to build a cluster or hijack a college computer lab for it to be worth doing   I expect the trading value will increase significantly over the next few weeks as the supply slows down; should be interesting.

[theymos]

The probability of winning per hash went from 9.90701E-12 to 5.12995E-12. So about double the difficulty.

[gould]

I'd be interested in seeing something like "expected bitcoins generated/day" next to (or in place of) the khash/s number. I'd rarely need to see the khash/s number since that won't change unless I make changes to the software or hardware.

[Insti]

I'd be interested in seeing something like "expected bitcoins generated/day" next to (or in place of) the khash/s number. I'd rarely need to see the khash/s number since that won't change unless I make changes to the software or hardware.

You can use the calculator at: http://www.alloscomp.com/bitcoin/calculator.php

If this is a feature request post in the Development & Technical Discussion Forum: http://bitcointalk.org/index.php?board=6.0

[Insti]

13/07/2010 0000000005a3f437d4a7f529fd4a7f529fd4a7f529fd4a7f529fd4a7f529fd4a

[satoshi]

The proof-of-work difficulty is currently 45.38.  (see http://www.alloscomp.com/bitcoin/calculator.php) 

It's about to increase again in a few hours.  It's only been 3-4 days since the last increase, so I expect it will increase by the max of 4 times, or very nearly the max.  That would put it at 181.54.

The target time between adjustments is 14 days, 14/3.5 days = 4.0 times increase.

[Bitcoiner]

The proof-of-work difficulty is currently 45.38.  (see http://www.alloscomp.com/bitcoin/calculator.php) 

It's about to increase again in a few hours.  It's only been 3-4 days since the last increase, so I expect it will increase by the max of 4 times, or very nearly the max.  That would put it at 181.54.

The target time between adjustments is 14 days, 14/3.5 days = 4.0 times increase.

Holy....

Satoshi, what happens if the rush dries up for a bit; some of the slashdotters or whoever get tired? Does the difficulty ever go back down?

[knightmb]

The proof-of-work difficulty is currently 45.38.  (see http://www.alloscomp.com/bitcoin/calculator.php) 

It's about to increase again in a few hours.  It's only been 3-4 days since the last increase, so I expect it will increase by the max of 4 times, or very nearly the max.  That would put it at 181.54.

The target time between adjustments is 14 days, 14/3.5 days = 4.0 times increase.

Holy....

Satoshi, what happens if the rush dries up for a bit; some of the slashdotters or whoever get tired? Does the difficulty ever go back down?

If I'm reading the source code correctly, it should go up and down based on how much CPU is being thrown at it. So if someone rented a super computer to drive up the difficulty for a week, then it vanished, the difficulty should float back down.

[satoshi]

It adjusted to 181.54 a few minutes ago.  Typical time to get a block is about a week now.

The difficulty can adjust down as well as up.

The network should be generating close to 6 blocks per hour now.

[RudeDude]

I'd be interested in seeing something like "expected bitcoins generated/day" next to (or in place of) the khash/s number. I'd rarely need to see the khash/s number since that won't change unless I make changes to the software or hardware.

I think the web c alc does a good job by showing likelyhoods based on khash speed:
http://www.alloscomp.com/bitcoin/calculator.php

That way you can see there is no guaranteed time horizon.

[knightmb]

It adjusted to 181.54 a few minutes ago.  Typical time to get a block is about a week now.

The difficulty can adjust down as well as up.

The network should be generating close to 6 blocks per hour now.

Yeah, I've noticed the "10 second blocks" are gone, replaced with 419 and 741 second block generation with no more in the last 20 minutes. That should keep those server farms on hold for a while  

Now, correct me if I'm wrong, but now that block generation is taking a lot longer, doesn't that mean that the lucky person who got the block is going to take a lot longer to be verified by the network that he/she was the winner before they could ever spend it?

[satoshi]

Yes, about 20 hours.  (120 conf / 6 blocks per hour = 20 hours)  That's the normal length of time before you can spend it.  You know long before that that you won one.

[knightmb]

Yes, about 20 hours.  (120 conf / 6 blocks per hour = 20 hours)  That's the normal length of time before you can spend it.  You'll know long before that that you won one.

So if the difficulty was increased so high that it took a day to find a winning block, that means the lucky winner would have to wait 120 day before they could spend it or about 4 months if everyone else was averaging about the same speed? Seems like at the high end of the difficulty, there is an issue with coin generation vs. being able to put it into circulation by spending. Wouldn't the long delay cause a lot of generated coin to be lost because anything could happen to the PC that won in a long amount of time if the winner had to really wait that long? They might un-install the program or the computer get eaten by a virus or power surge well before then.

[Bitcoiner]

Yes, about 20 hours.  (120 conf / 6 blocks per hour = 20 hours)  That's the normal length of time before you can spend it.  You'll know long before that that you won one.

So if the difficulty was increased so high that it took a day to find a winning block, that means the lucky winner would have to wait 120 day before they could spend it or about 4 months if everyone else was averaging about the same speed? Seems like at the high end of the difficulty, there is an issue with coin generation vs. being able to put it into circulation by spending. Wouldn't the long delay cause a lot of generated coin to be lost because anything could happen to the PC that won in a long amount of time if the winner had to really wait that long? They might un-install the program or the computer get eaten by a virus or power surge well before then.

I think that the overall network is generating the same amount of blocks regardless of the difficulty; the difficulty is intended so that the network generates a block in a relatively constant amount of time. Therefore, this confirmation time should always be around the same.

Satoshi or anyone else can correct me if I'm wrong

[satoshi]

Right, the difficulty adjustment is trying to keep it so the network as a whole generates an average of 6 blocks per hour.  The time for your block to mature will always be around 20 hours.

The recent adjustment put us back to close to 6 blocks per hour again.

There's a site where you can see the time between blocks, and since block 68545, it's been more like 10 minutes per block:
http://nullvoid.org/bitcoin/statistix.php

[knightmb]

Ah ok, cool. I continue to be astounded by how much thought was put into this system to keep it balanced, nice job!

[RHorning]

Now, correct me if I'm wrong, but now that block generation is taking a lot longer, doesn't that mean that the lucky person who got the block is going to take a lot longer to be verified by the network that he/she was the winner before they could ever spend it?

No, this isn't correct.  Finding the hash requires a whole bunch of effort, but the process of verification that the "winner" has found a matching block is by comparison a trivial exercise and doesn't take all that long.  Once they have found the block, they can spend those coins right away.

What this does mean is that the coin allocation system has now become a lottery, where new winners are receiving a block of coins worth a whole lot more (due to exchange rates and scarcity) than earlier blocks which were in comparison relatively trivial in value.  My question is, how valuable will this "lottery" become in the long run (in terms of Euros or Dollars per block generated)?

Essentially what is happening is that the computer is picking a random sequence of numbers (like a lottery) and if that computer happens to pick the correct sequence of bits, you "win".  The change in difficulty is something akin to playing a lottery that has you only picking six numbers vs. one with fourteen or a hundred numbers to win.  The odds are actually worse for a bitcoin block than even the worst of any normal lottery that has ever been conceived at the moment.

[ByteCoin]

In the Economy subforum, I have just written a post titled "Get rid of 'difficulty' and maintain a constant rate" which outlines a scheme which a new version of the BitCoin software could use to keep the rate of block generation absolutely constant at the cost of a slight increase in network traffic.

I would be very grateful for your comments.

ByteCoin