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1  Alternate cryptocurrencies / Altcoin Discussion / Re: BTC/NMC merged mining available for testing on: July 22, 2011, 06:57:23 AM
Just because 50 NMC took just as much to mine as 50 BTC doesn't mean that anyone's willing to spend 50 BTC on 50 NMC (one domain name) - that's a ridiculous price for one domain name (and nobody uses NMC to buy anything other than domain names at this point). If you have one NMC you're going to have to sell them for a lot less than one BTC, if anyone is going to buy them from you.

There is no reason to believe that 1 NMC will be equal to 1 BTC due to the perceived value of the two.  However, since both are mined at the same time, there's reason to believe that the exchange rate for both will become mostly fixed to say 10 NMC per 1 BTC, which essentially means the 21m coins cap for BTC has just gone up 10%.  If 1 BTC were considered a dollar, an NMC could be considered a dime.  Add in more currencies and the cap will go up even more, leading to an inflationary currency instead of a deflationary one that many were hoping for.
2  Alternate cryptocurrencies / Altcoin Discussion / Re: BTC/NMC merged mining available for testing on: July 17, 2011, 07:20:04 PM
The cost of mining BTC will stay equal. The only way that merged mining would be able to devalue BTC is if people start caring more about NMC (or any other currency) and they sell their BTC for it.

I never said it wouldn't stay equal.  However, by merging all these other ones into it, you effectively could get 100 different other ones at no cost to you.  Why would the average person only want to mine in one currency when they can do it in 100 different ones?  By not doing so, you're effectively getting only 70% (assuming BTC are worth 70% of the worth of all 100 currencies) compared to what other people are getting.  People wouldn't need to necessarily care about currency X as long as the currency still has a trade value for something with a more widespread purpose (BTC).

However, let's assume that people don't care about all these other currencies.  What's going to happen is there will be massive inflation in those currencies due to merged BTC mining and then people will start rejecting those currencies, causing them to fail.

Quote from: JohnDoe
To me, saying that merged mining will devalue bitcoins is akin to saying that printing more yens will devalue the dollar.

No, this is akin to saying instead of just being able to print more yen, you'd be able to print JPY, USD, CAD, AUD, ZWD, etc at the same cost in resources.  People that have JPY, USD, CAD, or AUD will be in jeopardy of devaluation and eventually a failed currency.  People with ZWD won't care as much because it's basically worthless and failed already.  Because all these other currencies are being printed at the same time as JPY, people can effectively use the other currencies as substitutes for JPY, causing effectively an increase in the JPY money supply and driving its worth down along with all the other printed currencies.

Quote from: nodemaster
I'd agree to the devaluation arguments if (and only then), when we could mine for new coins endlessley. But this is not the case. After for example all bitcoins have been mined merged mining assures, that there are still many people mining for perhaps another blockchain making sure the bitcoin blockchain is still strong.

This is effectively what can happen.  Instead of being limited by the 21m coins, you're creating these other pseudo-BTC.  With enough time and as long as they haven't failed, there will be a tightly knit relationship between those currencies.  Also, BTC won't reach its limit for another 100 years, and that's plenty of time for it to fail.

I'm not saying this will happen but I think it's a very likely scenario.  However, I'm fairly certain that what will come out of this will be a lot of failed currencies that might have had a chance to exist if they weren't merged.  I don't think there has ever been a time when you could print 100 different currencies by only printing 1 so there isn't anything directly related to compare against.  I see pseudo-BTC will come out of it (thus, leading to devaluation and a higher risk of failure) while you and JohnDoe don't.  What's certain though is that all currencies that inflate beyond sustainability end up in failure.  IMO, there is a lot more downside to merged mining than upside.
3  Alternate cryptocurrencies / Altcoin Discussion / Re: BTC/NMC merged mining available for testing on: July 17, 2011, 10:36:33 AM
NMC does have a purpose though... unless other blockchains with a purpose were started, why would anyone mine them?

It's not just about purpose.  As a real world example, take the USD.  It serves a purpose and has been the reserve currency for over half a century.  If they start printing a lot more money, would you rather someone paid you in USD or a currency that doesn't need to go through major devaluation like AUD?

Also, not everyone believes in NMC.  Anyone can come up with blockchains with a "purpose" that a niche will enjoy mining in.  When mining in 100 currencies costs the same as mining in 1, people won't care that they're mining in a currency that's used to pay for videos of someone torturing insects.  If you're not for that cause, someone else will be and you not mining in a pool of only 20 currencies with ideas you believe in will cause you to earn much less than the people that are mining in all of them.

Remember once NMC and BTC are both mined at the same time, the exchange rate between the two will eventually be fairly constant.  It'd be like the BTC was considered as a USD $20 and an NMC a USD $1, effectively increasing the money supply of the base currency (BTC) and devaluing both.
4  Alternate cryptocurrencies / Altcoin Discussion / Re: BTC/NMC merged mining available for testing on: July 17, 2011, 10:04:16 AM

What about the economic performance disadvantages of the respective currencies?

Won't this devalue bitcoin?

I think this would devalue bitcoins, as well as any other coins that get added.  Hundreds of new coins will be added at no extra cost (as markm already confirmed).  All of those coins will be at jeopardy of losing value and might even get rejected.

This would be akin to everyone being able to print their own money and trying to get others to accept it.  With a few select currencies, it's easy for them to succeed.  With thousands to choose from, people aren't going to accept every type of payment someone thinks up.

As good as it might sound, especially for miners, this will probably lead to demise of many currencies, many of which probably didn't have a chance anyway but some that might have had a chance will die off as well.

Isn't the allure of BTC and other currencies like NMC the idea that an entity isn't able to print money whenever they feel like it?  This would be the same thing.  Miners would be mining mainly for BTC while in the process, printing extra money that will end up having a nearly constant exchange rate between BTC, NMC, etc, thus increasing the money supply and devaluing all of those currencies.  People are worried about the US having to print money to stay afloat because it could eventually lead to hyperinflation making the USD worthless.  All the coins following this path will also have that same risk.  People want to adopt BTC because they believe that can't happen with the currency.

For all of our sake, I hope everyone will reject this idea and it won't make it into any official branch, or even unofficial ones.
5  Bitcoin / Project Development / Re: [20 BTC] Multithreaded Keep-alive Implementation in Bitcoind on: July 17, 2011, 07:46:34 AM
I've been testing and debugging the patches against the 0.3.23 version.  I think I've got most of the problems figured out but there is still a critical problem that's made me lose out on 3 blocks so far.

First, the fast getwork parsing doesn't work if the client doesn't send the id without quotes.  This will allow it to send the id with or without quotes:

ThreadRPCServer3 in rpc.cpp:
Code:
       if ((strRequest.find("\"getwork\"")!=std::string::npos) && strRequest.find("[]")!=std::string::npos)
            std::string id;
            size_t p = strRequest.find("\"id\":");
            if (p != std::string::npos)
            {
                size_t ep = strRequest.find(" ", p+5), e;
                if((e=strRequest.find(",", p+5))<ep) ep = e;
                if((e=strRequest.find("}", p+5))<ep) ep = e;
                id = strRequest.substr(p+5, ep-p-5);
            }

Second, the locking problems seen are mostly due to the mutex being non-recursive.  Changing mGetWork to recursive_mutex instead of mutex, along with the iterators for it, should fix the problem.

Third, the CheckWork done in getwork assigns a value that should be returned but to a variable in the wrong scope.  This has been addressed earlier.

Some of the locking seems to be off.  An example would be:

CommitTransaction in main.cpp:
Code:
       // Broadcast
        if (!wtxNew.AcceptToMemoryPool())
        {
            // This must not fail. The transaction has already been signed and recorded.
            printf("CommitTransaction() : Error: Transaction not valid");
            return false;
        }
        wtxNew.RelayWalletTransaction();
+        SyncGetWork(4);
    }
-    SyncGetWork(4);

The comment for SyncGetWork says cs_main must be held but before being called, but that's not the case with the patch before the above change.

Another one would be:

AddToBlockIndex in main.cpp:
Code:
   if (pindexNew == pindexBest)
    {
        // Notify UI to display prev block's coinbase if it was ours
        static uint256 hashPrevBestCoinBase;
-        CRITICAL_BLOCK(cs_mapWallet)
+        CRITICAL_BLOCK(cs_mapWallet) {
            vWalletUpdated.push_back(hashPrevBestCoinBase);
+            hashPrevBestCoinBase = vtx[0].GetHash();
+        }
-         hashPrevBestCoinBase = vtx[0].GetHash();
    }

This one may or may not matter depending on how many threads call it (I believe only one thread runs this function but I'm not 100% sure).  However, this related to crashes I've been seeing right after writing out the block and before sending out the proof of work.  The call to vtx[0].GetHash causes a crash in the Serialize function due to the assertion that nSize >= 0.  I believe it's due to vtx[0] being corrupted but the event is rare at such high difficulties.  I don't see the problem with the test network but it happens on the live one.

One thought I had is that the live one has more transactions and appending enough of them would trigger the crash.  If this is the case, one cause might be the changes JoelKatz has made that'd allow vtx to get updated elsewhere (from another client calling getwork?).  Another one may be vtx is a vector and whenever it resizes, the structures related to each object inside vtx isn't correctly copied over (I didn't see any copy constructors).  I was able to get a block through when I commented the above out so that might be a sign that I'm on the right track but I'd like to see it get a few more blocks before I can rule out that it wasn't just a random event (initially, crashes on the test network were random and I've yet to see any on it since the fixes mentioned earlier).

These high difficulty levels are making it really troublesome to debug locking/race conditions.  It'd be nice if one of the big pools try out various things to see if they also experience the crashes (and possibly end up not getting credit for the block) and try out various fixes to see if it fixes the problem.  I haven't seen anyone mention these crashes so for all I know, it's just some compiler/machine issue.  But then again, it doesn't seem like anyone's tried it with the fixes that doesn't lock up.
6  Economy / Marketplace / Re: The fastest HD 69xx miner. 250 BTC. on: July 10, 2011, 01:34:41 AM
Have you used the modified phatk kernel yet.   Some have been showing it to have a 2%-3% increase.  I rather suspect that eliminates the differences between this client and phoenix.   mrb even acknowledged that the recent change was one that hdminer already had.    Which since, like you I suspect that the difference is closer to 2% rather than 6% makes hdminer obsolete.

I get better hash rates with the poclbm kernel on the 6990.  I tested a few of the optimizations people were trying out recently but those made no difference or made things worse.  On the 5970, the modified phatk is much better.

However with the recent Ma changes and some other tweaks, I get better rates than the ones shown for hdminer.  At 915, I get 817.6 compared to hdminer's 802.  At 960, I get 857.8 compared to hdminer's 840.  It doesn't necessarily mean that hdminer is slower since I don't have hdminer to try out but it does show that you can get better numbers than the published hdminer ones and anyone thinking of getting it should think twice about doing so.  Perhaps there'd be another 2-3% increase if the tricks hdminer uses were used as well, as the Ma one was only about half of the 6% difference.

Upgrading to Catalyst 11.5 did increase hash rates a bit over 11.4.  11.7 is supposed to be even faster but it's still beta and I heard it was buggy.
7  Other / CPU/GPU Bitcoin mining hardware / Re: What ATI 6990 is the best, MSI, XFX ou HIS? on: June 28, 2011, 08:20:42 PM
XFX has a double lifetime warranty (so you can transfer the warranty once to someone else if you sell it).  They will also accept warranties if you use the OC position.  Sapphire will also warranty it if you use the OC position but the warranty is only one or two years.  From what I've heard, all other brands might void the warranty if you put them in the OC position.

I think HIS will give you the most amount of accessories (crossfire connector, PCI-e adapters, DisplayPort converters, etc).  MSI will include covers to protect the connectors.  XFX includes the least amount of accessories.
8  Other / CPU/GPU Bitcoin mining hardware / Re: Yet Another Video Card Comparison... on: June 28, 2011, 09:48:12 AM
6990 is off by a wide margin.
For 760+ mhash/s you would have to OC past 900mhz so power consumption just for the card itself will be 450-500+ watts

That's not true.  At 880mhz, I'm getting 379.8 mhash/s for each core (759.6 mhash/s for the card).  With finely tuned over/underclocking, I was able to get 3x6990 to do a stable 2.41 ghash/s in under 1300w for the entire system (efficiency of 1.85 mhash/J for the entire system, 2.00+ mhash/J for each card).  I'd guess the system w/o the GPUs is around 100-150w, which means each card is doing about 400w, maybe less.  I can overclock them even higher as well but I wanted to keep the system at safer amperage levels.  This was before software tweaks I made that pushed it 3.5-4.0% faster (3% of it thanks to bitless's Ma optimization).  I don't know how much power they use now but they're doing 2.50 ghash/s now.  I don't think power has changed too much since temps are about the same as before (all but a "defective" core are below 80C on air cooling).  I still have plenty of room to get it even faster but I'll be losing a lot of efficiency in the process and I'll be over the power usage constraint I placed upon myself for the whole 3 card system.

On the other end of the spectrum, I can tweak the system to be at least as efficient as 2.10 mhash/J (or over 2.35 for the card) while still maintaining a hash rate above 2.0 ghash/s.  I'm sure all the efficiency numbers are even higher now with the 3+% speedup.  The PSUs and GPUs matter quite a bit at the higher OC levels.  I've seen GPU cores that require a lot more voltage to achieve the same rate as another one.  And if you're unlucky (like me), you'll get a card with cores that are well over 10C higher than the other core on the same card, making it so you can't overclock as much while using up more power due to the extra heat.

I run Linux and use the phoenix miner with the poclbm kernel.  It's the fastest miner for me and beats even hashkill in raw speed while having less than 1% stales.  My numbers are now higher than hdminer now (@915, I get 817 mhash/s vs hdminer's 802. @960, I get 857 mhash/s vs 840).  I think my hardware tweaks put them over the top, as the software tweaks haven't quite reached the 6.4% hdminer claims so I'd be interested in finding out if hdminer would get even better numbers with my setup.  I'm just not willing to pay the hefty price to find out.
9  Bitcoin / Mining support / Re: x2 6990 + x1 6950 problems, help please! (2 BTC reward for fix!) on: June 26, 2011, 02:42:36 AM
Download LinuxCoin and put it on a thumb drive or CD to see if you're able to run it on all the cores.  You should see two devices for each 6990 card.
10  Bitcoin / Mining / Re: How many liquid-cooled 6990s can a 1500W PSU push? on: June 25, 2011, 10:09:58 PM
You should follow the advice of what water coolers are telling you.  Don't do it unless you're fine with throwing away money and know what you're doing (or are willing to spend a bit of time learning).  It's not going to be easy/cheap to cool several of these cards.

Whether you should go for 3 or 4 cards depends on whether or not you want to overclock them.  With 3 overclocked cards, you can easily approach the same power usage as 4 cards at stock speeds.  With 4 slightly overclocked cards and some memory underclocking, you could be hanging around 1800w, depending on how good the PSUs are.  You'd want two PSUs to do 4 cards.  With 3, you're pushing it with a single PSU and should go for 2 PSUs.  You might be looking at 900-1300W just for the cards themselves.  You'll want to stay under 1440W total draw on a 120V/15A breaker, or 1920W on a 120V/20A breaker to be on the safe side.  3 cards would be safer and cost less.  4 cards is a fire hazard.
11  Other / Beginners & Help / Re: Can bitcoins be lost? on: June 25, 2011, 08:06:14 PM
You seem to be trying to convince me that being rich is a bad thing.
No. I am not. You can go back and read my entries again if you wish to continue.

So you're basically not a risk taker and are fine with being mediocre with no chance of becoming rich?  That's fine for risk adverse people but there are plenty of others that enjoy investing/saving in hopes of becoming rich.
12  Economy / Marketplace / Re: The fastest HD 69xx miner. 250 BTC. on: June 25, 2011, 04:13:35 PM
hdminer's target market is not you the home user, but cluster owners who operate 20+ GPUs and are power or cooling constrained (eg. power circuits at 80% utilization per the US National Electric Code), yet need that +6.3% perf improvement without increasing power consumption or cooling needs.

I don't know what speeds they're getting at what temps but I'm able to do 2.43GH/s with 3 6990s at 1300w (10.83A) after 15 mins when the fans have been running at 100% for some time and temps are higher.  Temps are all below 80C on air cooling on all cores except for a defective one that's always 12-20C higher than the other core on the same card (I limit the overclocking on that core so temps remain in the low 80s; perhaps I only need to reapply some thermal paste on it but I'm RMAing it to avoid any warranty issues).  At times (probably when the AC kicks on), temps will be in the high 60s to low 70s.  The thermostat is in another room and set to 76F in a very hot climate (currently over 100F outside) so it'll go on and off at various times.  This is with an enclosed HAF 932 case with one 200mm fan removed and 5 120mm fans added.

What seems to makes a big difference is the PSU used.  10.83A on a 15A breaker (it's actually on a 20A breaker but I'm treating it as 15A for safety reasons) means I still have 1A to overclock it to possibly 2.50GH/s.  I've also got plenty of room to add more cooling if necessary to bring the temps down.  I'm comfortable with them running in the 70s and spiking into the low 80s for a short period of time.  I've used a cheaper PSU and could only do 2.38GH/s while pulling over 1380w.  I use two PSUs but only swapped out the main one.  Mind you, the better main PSU isn't high end at all so if you're willing to pay a hefty premium, perhaps it'll be able to do better.  The secondary PSU is on the cheaper side so that could be improved as well.  The extra fans I'm using are cheap Yate Loons and not something expensive like the jet propelling Deltas that can pull in over 2x as much air flow.  I don't even have a big external fan blowing on it.

I'm also running Linux, which means I'm more limited on the things I'm able to tweak (but with the custom tools I've made, I think I'm very close to what someone on Windows is able to do).

If your customers are getting the same rates or less than what I am with those constraints, they're spending a lot of money for things they can tweak on their own.  At 1300w for 2.43GH, that's an efficiency of almost 1.87MH/J for the entire machine.  When the time comes, I can make it go slower and be above 2.1MH/J (likely more) for the entire machine or above 2.4MH/J per card.

Also, assuming that hdminer is 6.3% faster, that'd mean they need to be doing at least 76.2GH/s to do better than spending the same amount of money on extra 6990s.  I agree with Jack of Diamonds that you're pricing yourself out.  If people do the proper research, they wouldn't be paying 250 BTC, let alone 100 BTC for something that is 1.2-2% faster. At 50 BTC and 2%, you'd want to do at least 49.7GH/s to do better than adding the same amount in extra hardware.  I also suspect that it being faster means it will probably use a little more power, though not necessarily in the same proportion as the increase.
13  Economy / Marketplace / Re: The fastest HD 69xx miner. 250 BTC. on: June 25, 2011, 06:10:31 AM
From comparing the speeds I'm getting to hdminer, the miner isn't 6+% faster, it's only 1.2-2% faster.  I'm using Catalyst 11.4 without downgrading and underclocking the memory so the difference could be even less than that (11.5 is supposed to give it a few Mh boost and not underclocking it would increase hashing rates by 0.5-1.5Mh/s).

Here are the rates (per core) I get at various speeds in the overclocked position using the phoenix 1.48 miner with the poclbm kernel:

880 - 379.8
900 - 387.0
905 - 389.6
910 - 391.9
915 - 393.4
920 - 396.0
925 - 398.2
950 - 408.5
955 - 410.8
961 - 412.6
966 - 414.6

Those numbers are near the higher end of the spectrum but not the very top.  The numbers are sustainable and not just one time blips that timing/thread switching might inflate.  At 880, hdminer was actually 1.8% slower (759 vs 746).  For the 915 and 960 settings, hdminer was faster (@915, 786 vs 802 = ~2.0%, @960, 824 vs 840 = ~1.94%).  These are using numbers that would favor hdminer more (lower hashing rates than optimal and rounding my rates down).  More optimal numbers would probably put it closer to a 1.2% difference.

Using $17 as the value of a BTC, 250 BTC = $4,250.  If the cost of a 6990 were $740, that'd be 5.74 6990s.  Assuming hdminer was 2.0% faster, you'd need over 295.6 6990s to make a profit.  So unless you're running an operation that exceeds 248GH/s, you shouldn't buy hdminer.  I'd be surprised if there are several people with that much capacity, let alone even one.  It'd be even worse if hdminer were only 1.2% faster.
14  Other / Beginners & Help / Re: Historical Difficulty? on: June 25, 2011, 02:56:48 AM
And in about 10 days, if the difficulty jumps up another 50%, it'll reduce that 0.636 BTC down by a factor of 1/1.5 = 0.666, which would make it 0.4236 BTC.  10 days after that, another 50% jump would reduce it to 0.2821 BTC, then 0.1879 BTC, etc.  This is why you should never estimate earnings with no difficulty increases.  50% increases every 10 days is a lot but it hasn't really been letting up.  33% increases every 10 days is probably more reasonable but even at that slower rate, BTC needs to be at least $30 to possibly break even on new rigs.
15  Other / Beginners & Help / Re: Historical Difficulty? on: June 25, 2011, 02:44:59 AM
The higher the difficulty, the longer it'll take for you to mine.  The recent 57% jump in difficulty means you'll average out to making 1/1.57 = 0.636 of what you were making before.  So if you were making 1.0 BTC yesterday, today you'll be making 0.636 BTC in the same amount of time (disregarding variance).
16  Other / Beginners & Help / Re: Can bitcoins be lost? on: June 25, 2011, 02:33:26 AM
In the far future, when for many years, it appears that only 1,000 Bitcoins are in circulation, the rest presumed lost, could someone dump a million Bitcoins on the market?

In this scenario, the presumed lost coins weren't really lost at all; they were saved.  It does show that whoever saved those million Bitcoins have gained tremendously from saving.  However, when they start to dump those coins onto the market, it would appear to be inflationary as the prices of everything goes up to reflect the amount in circulation.

It would be similar to someone finding a 2000 year old pottery and someone willing to pay $1m for it due to its presumed rarity.  However, if a year later some finds a site with thousands more of those same pottery, the presumed value would drop significantly, even though the amount produced hasn't changed at all, only the ones in circulation.
17  Other / Beginners & Help / Re: Has the ship sailed on mining profitability? on: June 25, 2011, 02:23:09 AM
Most people concentrate on the price when considering when to stop mining or if it'll be profitable.  IMO, that's only a small part of it.  What few people fail to consider, and is much more important right now, is the difficulty.  Sure, if you're not paying for electricity, you'd always be making a profit... if you don't consider anything else.  When the difficulty goes up so high that you'd be spending a month to get 1BTC with your 5GH/s setup, would you keep on mining, even with free electricity and rigs you've already paid off?  If you still are, you're risking damaging a few hundred/thousand dollars worth of equipment for $100 in profit (I doubt the price of BTC will be that high any time soon).  You'd make more selling that equipment.

If the difficulty keeps on going up at a 33% rate every 10 days, you're probably looking at 4-5 months before you should consider throwing in the towel, unless the price was astronomical.  The difficulty has been going up much more than that and the halving of a block to 25BTC is coming much sooner than expected.

You'd only want to start mining with new rigs now if you believe that the difficulty will slow down or reverse course very soon.
18  Other / Beginners & Help / Re: Historical Difficulty? on: June 25, 2011, 02:05:37 AM
https://spreadsheets.google.com/pub?hl=en&hl=en&key=0AmcTCtjBoRWUdHVRMHpqWUJValI1RlZiaEtCT1RrQmc
19  Other / Beginners & Help / Re: Can bitcoins be lost? on: June 25, 2011, 02:00:52 AM
The Bitcoin currency was designed to be deflationary.  Most other fiat currencies are inflationary.  What that means is with Bitcoins, the longer you save, the more valuable it would become, so long as the currency succeeds and people trust it.  With most other currencies that aren't backed by anything but trust, they can print as much money out of thin air as they want, so long as trust is maintained.  However, saving money with these inflationary currencies means you'll lose money the longer you save.  Right now many worldwide fiats are becoming more fragile and trust is gradually being lost as countries try to print more money to bail out the rich people, allowing them to maintain their wealth with the newly printed money while everyone else gets devalued money in return.  The disparity between rich and not rich has widened at a greatly accelerated rate since the economic collapse.
20  Other / Beginners & Help / Re: Whitelist Requests (Want out of here?) on: June 24, 2011, 11:09:17 AM
I'm a software developer and have known about Bitcoins since the beginning but didn't start mining until earlier this year.  Can I get whitelisted?
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