Are GPU's Satoshi's mistake?

[FreeTrade]

We all know that ordinary CPU's are useless for mining and that only using GPU's with specialized programs gives a reasonable return.

Did Satoshi mean it to be this way? I can't imagine that he did. Everything else is so well thought out, I imagine that his vision was that anybody with access to a computer would be able to effectively turn electricity into Bitcoins at a fairly reasonable return. If that were the case, it would certainly be easier to distribute BTC.

Did Satoshi not forsee that GPU's would be much more efficient, thus reducing mining to the GPU'd few?

[error]

I suspect he never foresaw either GPUs or mining pools.

[Serge]

At the same time every computer literate person realizes that computing power only going to increase with time.

[memvola]

Did Satoshi not forsee that GPU's would be much more efficient, thus reducing mining to the GPU'd few?

He didn't have to foresee anything that specific. It was obvious that mining would be dominated by specialized people and specialized hardware. If there weren't GPU's to compete, FPGA's would be very competitive since they consume far less power than CPU's. If FPGA's weren't, we'd expect ASIC solutions sooner.

So it's not a flaw, it's just inevitable. I'm guessing you're inspired by new proof-of-concept currencies that are CPU-friendly. Keep in mind that if they get to a critical size, it's also inevitable for them to be dominated by specialized hw.

[FreeTrade]

So it's not a flaw, it's just inevitable. I'm guessing you're inspired by new proof-of-concept currencies that are CPU-friendly. Keep in mind that if they get to a critical size, it's also inevitable for them to be dominated by specialized hw.

I agree it is inevitable - but it is still a flaw.

The flaw is not that it is possible for specialized equipment to out perform general purpose computers. As you say, that is inevitable - it is the factor by which they do.

GPU's might outperform CPU's by 10:1 - So I must spend $50 in electricity for every $5 in BTC

However, if GPU's outperformed CPU's by 1.1:1 - then I'd spend $5.50 for every $5. You'd still have specialized hw, but you'd have general purpose computer participants too.

The flaw then is the ratio at which specialized hardware outperforms, and not having designed to minimize that ratio.


 

[Serge]

it doesn't matter how you call it, Pentium, Xeon, GPU, FPGA, ASICs, Quantum computing

it's a computing power which over time going to increase. I don't think Satoshi expected people would be mining Bitcoins in 20 years on the same Pentiums it was developed to run on at the time.

[Meni Rosenfeld]

The jury is still out on whether this is a problem. Having ordinary PCs viable for mining causes a significant botnet risk, and while the idea of everyone being able to mine is appealing, it's not essential.

If this is agreed to be a problem, the hashing function can be changed to something for which ordinary PCs are more suitable, and it's possible this was Satoshi's plan.

I suspect he never foresaw either GPUs

I doubt that, GPGPU isn't exactly news. He might have not known a priori exactly how good GPUs are for SHA-256 but the idea would certainly have occurred to him and he could have investigated if he thought it was a relevant problem.

or mining pools.

I doubt that, someone who understands probability (which Satoshi does) and expects that many people will mine (which I believe he did), can't think that solo mining will be feasible.

At the same time every computer literate person realizes that computing power only going to increase with time.

This has nothing to do with it. This isn't computing in general becoming faster, it's about specialized hardware for this specific purpose putting people using commodity machines at a disadvantage. "Computing power increasing with time" benefits pros and amateurs equally.

Did Satoshi not forsee that GPU's would be much more efficient, thus reducing mining to the GPU'd few?

So it's not a flaw, it's just inevitable. I'm guessing you're inspired by new proof-of-concept currencies that are CPU-friendly. Keep in mind that if they get to a critical size, it's also inevitable for them to be dominated by specialized hw.

You're ignoring capital expenditures. At-home miners are leveraging existing hardware giving them a huge advantage over specialized businesses. To specialize mining, the advantage of the specialized hardware should be equally huge. This is the case with SHA-256, but not necessarily with a function chosen to require resources similar to the average PC.

[k9quaint]

I agree it is inevitable - but it is still a flaw.

The flaw is not that it is possible for specialized equipment to out perform general purpose computers. As you say, that is inevitable - it is the factor by which they do.

GPU's might outperform CPU's by 10:1 - So I must spend $50 in electricity for every $5 in BTC

However, if GPU's outperformed CPU's by 1.1:1 - then I'd spend $5.50 for every $5. You'd still have specialized hw, but you'd have general purpose computer participants too.

The flaw then is the ratio at which specialized hardware outperforms, and not having designed to minimize that ratio.

You have it backwards. GPUs are far more efficient than CPUs in electricity use.

[Meni Rosenfeld]

I agree it is inevitable - but it is still a flaw.

The flaw is not that it is possible for specialized equipment to out perform general purpose computers. As you say, that is inevitable - it is the factor by which they do.

GPU's might outperform CPU's by 10:1 - So I must spend $50 in electricity for every $5 in BTC

However, if GPU's outperformed CPU's by 1.1:1 - then I'd spend $5.50 for every $5. You'd still have specialized hw, but you'd have general purpose computer participants too.

The flaw then is the ratio at which specialized hardware outperforms, and not having designed to minimize that ratio.

You have it backwards. GPUs are far more efficient than CPUs in electricity use.

No, he means that specialized GPU miners in equilibrium will be close to breakeven and so spend ~$5 electricity per BTC (which ignores all other costs, but whatever), while he as a CPU miner will have to spend $50.

[mrb]

Not only did Satoshi planned for an increasing amount of power being thrown at mining, but he did know that GPUs would exel at it, way before any GPU miner even existed, in December 2009:

We should have a gentleman's agreement to postpone the GPU arms race as long as we can for the good of the network.  It's much easer to get new users up to speed if they don't have to worry about GPU drivers and compatibility.  It's nice how anyone with just a CPU can compete fairly equally right now.

[tvbcof]

At the risk of offending miners...

Seems to me that mining is something of a sideshow and and a system engineering problem who's solution does not matter very much as long as it works.  But I would suspect that Satoshi would have been aware of the possibilities for solving the chosen proof-of-work problem and put at least some consideration into it.  The evolution from CPU -> GPU -> ASIC overlayed with the rate of inflation seems to me to be yet another impressive (and probably non-accidental) happenstance.

I have some wonder about what will happen as ASICs come on-line and how that will occur, but don't understand things well enough to decide whether I have concern or not.  It does seem to me that a lot of the problems that could crop up should attackers gain the upper hand at such a juncture could be addressed by the 'sledgehammer' approach of addressing them in code.

[Meni Rosenfeld]

At the risk of offending miners...

Seems to me that mining is something of a sideshow and and a system engineering problem who's solution does not matter very much as long as it works.

None taken and I agree. And I say this as someone who mines, has been fascinated for years with the concept of monetizing distributed computing and was initially drawn to Bitcoin in large part due to its enabling of it, and whose primary skilled contribution to Bitcoin is analysis of mining pools reward systems.

But I think that people are vastly underestimating now the magnitude of the problems Bitcoin will face in the future related to the economics of mining. Maybe "mining for the masses" could play a part in the solution.

[FreeTrade]

You're ignoring capital expenditures. At-home miners are leveraging existing hardware giving them a huge advantage over specialized businesses.

Thanks - yes, I had forgotten this entirely. Factoring this in, I'm guessing that a sufficiently well designed CPU-friendly currency could make commercial mining entirely unviable. 

[FreeTrade]

Not only did Satoshi planned for an increasing amount of power being thrown at mining, but he did know that GPUs would exel at it, way before any GPU miner even existed, in December 2009:

We should have a gentleman's agreement to postpone the GPU arms race as long as we can for the good of the network.  It's much easer to get new users up to speed if they don't have to worry about GPU drivers and compatibility.  It's nice how anyone with just a CPU can compete fairly equally right now.

Thanks - very revealing quote there. My reading of it is that he became aware of the GPU problem after the 'horse had already bolted' - and is thus appealing for a 'gentleman's agreement' for what he might have otherwise prevented in design from the outset.

[P4man]

bitcoin specific ASICs seems a bit of a stretch at this point, but I wonder can something like this not be used:
http://www.cast-inc.com/ip-cores/encryption/sha-256/cast_sha256-a.pdf

Anyone have an idea how to interprete the performance numbers and how they compare to our gpu's?

[FreeTrade]

The jury is still out on whether this is a problem. Having ordinary PCs viable for mining causes a significant botnet risk, and while the idea of everyone being able to mine is appealing, it's not essential.

Agreed, it is not essential - it's an aspect of the Bitcoin protocol. I'm not sure if I'm on the Jury or not, but if I were I'd have to agree with Satoshi and say CPU-friendly mining is a desirable feature to help drive adoption.

I'm interested in the new developments with Fairbrix and Tenebrix - but clearly Bitcoin has all the momentum.

[FreeTrade]

If this is agreed to be a problem, the hashing function can be changed to something for which ordinary PCs are more suitable, and it's possible this was Satoshi's plan.

My understanding is that this kind of agreement would require the agreement of the majority of the computing power of the BTC network and so is next to impossible? Am I mistaken that the Bitcoin protocol was built explicitly so that these are difficult to change, not easy?

[DeathAndTaxes]

bitcoin specific ASICs seems a bit of a stretch at this point, but I wonder can something like this not be used:
http://www.cast-inc.com/ip-cores/encryption/sha-256/cast_sha256-a.pdf

Anyone have an idea how to interprete the performance numbers and how they compare to our gpu's?

Bad.  Very bad actually.  The throughput is in Mbps.  A hash is based on 512 byte message. A bitcoin solution takes 2 hashes.  Thus Mbps/1024 ~= MH/s.

For their example FPGA it is in the ballpark of ~1Mbps.  The FPGA developers on this forum have achieved far more.

As for ASIC being a stretch.... it all depends on how big bitcoin gets.  If it gets large enough (i.e. 10% of the transaction volume of paypal) then someone will develop ASICs.  Likely though they won't be for sale and will be retained as a competitive advantage.  Imagine someone like Amazon installing a bitcoin hashing card (based on custom built) ASIC into 100K computers in their cloud.  They could still run virtualized instances on demand but the same "host" would also mine 24/7 on highly efficient hardware.

[DeathAndTaxes]

My understanding is that this kind of agreement would require the agreement of the majority of the computing power of the BTC network and so is next to impossible? Am I mistaken that the Bitcoin protocol was built explicitly so that these are difficult to change, not easy?

Exactly.  What makes it even less likely than other changes is that GPU have the majority of hashing power.  This GPU miners would in essence have to vote against their own interests.

[kjj]

bitcoin specific ASICs seems a bit of a stretch at this point, but I wonder can something like this not be used:
http://www.cast-inc.com/ip-cores/encryption/sha-256/cast_sha256-a.pdf

Anyone have an idea how to interprete the performance numbers and how they compare to our gpu's?

Bad.  Very bad actually.  The throughput is in Mbps.  A hash is based on 512 byte message. A bitcoin solution takes 2 hashes.  Thus Mbps/1024 ~= MH/s.

For their example FPGA it is in the ballpark of ~1Mbps.  The FPGA developers on this forum have achieved far more.

It is even worse than you think.  All commercial SHA coprocessors are built for streaming, which doesn't work for bitcoin.