Quote from: rbdrbd on May 23, 2013, 01:34:39 PM

Quote from: wire on May 23, 2013, 08:17:19 AM

guess many insiders do it at least the ones who are capable to write opencl code and they wont share their code with just everyone as long as they are making profit.

as soon as they dont make any profit anymore with mining they will sell the code, then when not making profit with selling anymore you will see it on github for free.

If i am wrong prove it and publish working code

The data does not suggest this.

According to mtlrt, at current N = 256, a top end video card could get around 2.004 MH/s with a HD6990 and his kernel. That means for a mid-size GPU farm owner with 50 7950s/7970s or such may see around 75MH/s or so, or more (a very rough estimate, based on performance difference between 6990 and 7950/7970).

According to yacoind:

Code:

# ./yacoind getmininginfo
{
   "blocks" : 68606,
   "currentblocksize" : 2275,
   "currentblocktx" : 5,
   "difficulty" : 3.01596016,
   "errors" : "",
   "generate" : false,
   "genproclimit" : -1,
   "hashespersec" : 0,
   "networkhashps" : 72345435,
   "pooledtx" : 5,
   "testnet" : false,
   "Nfactor" : 7,
   "N" : 256,
   "powreward" : 20.80000000
}

Current network hash rate is estimated at 72.3MH (this is with the newest yacoin source). With just ONE mid-range GPU farm owner being able to generate more than the current YaCoin network at this point, this does not look like there are ANY "GPU insiders" mining. Or if there are, they are not hitting it with a decent sized GPU farm. However, this also raises issues of the possibility of a 51% attack if one or two ill-meaning farm owners get a hold of a GPU miner. Let's hope mtrlt either holds on to his GPU kernel like it appears he has to this point, or if released, it's released to all. Anything else risks the stability of the YaCoin network.

The other risk here is a possible inadvertent "difficulty attack" if this N=8192 issue is real and a GPU miner is released to all. At that point, difficulty would increase sharply, and once N=8192 is hit, drop off a cliff. I wonder if there would be enough hash power after that to get it back to a sane level without necessitating a hard fork like feathercoin has done (maybe WindMaster has more input on this). Also, whether POS minting would be enough during that time to validate new transactions on the network. Maybe others much more knowledgeable than I on these matters could comment.

I am hopeful that the 8192 issue is a more fundamental problem with GPU mining on this coin. Most serious GPU miners have 7950s or 7970s instead of 6990s, so this issue may be run into even earlier on one of those cards, as the memory amount and bandwidth on the 7950 at least is a good amount less than on the 6990. This community is ingenious, however, as the litecoin experience had shown. But if you had the guy that wrote the scrypt kernel for reaper having issues at 8192 after trying multiple lookup gap and TMTO hacks, then there is some real life for this coin I think.

It sounds more like a kernel level bug to me. Note that the author said it was throwing invalid hashes, not a very slow rate of valid hashes.