I don't know yet. It just stops working on its own.


Yes, in fact I tested CPU mining up to N=2^19=524288, where my puny Phenom x6 1055T got around 12 H/s.

This is true.  I'm not going to dispute that.  



Thanks for the link, I'll have a read of your memcoin thread.  In a quick glance through, I'd say we're both in agreement YACoin's starting N was far too low, at least.



Roger that.

Validation of the previous portion of the block chain would be happening at the original N at the time that block was mined, not at the current value of N.  I think where we would get into trouble is when it takes as much or more time to validate a block than the target time between blocks (1 minute).  Somewhere in the next few years, I'm sure the debate of storing the entire blockchain on every user's computer will be discussed more and more among all the coins.

I'm benchmarking large values of N right now.  The highest I've benchmarked so far is N=262144 on a dual Xeon E5450 server (which is ~4 year old server technology), and have around 30.55 hashes/sec at that value of N, which would be hit on June 23, 2015.  Looks like mtrlt benchmarked his 6-core Phenom to the next N increment beyond that (which I'm benchmarking right now) and got around 12 hash/sec.

Based on the slope of the N increases over the long run, Moore's Law (not that it's a hard and fast rule) will begin overtaking the N increases and average hash rates per user will start rising again.  I don't necessarily subscribe to Moore's Law actually being valid at the immediate moment, looking at the actual processing power changes over the last 18 months.  However, out in the future, YACoin's Nfactor++ events become less and less frequent.

I know about Moore's Law. But there're still risks in it. Because current technology is reaching its limitation, remember that Intel/AMD/Nvidia still stick to 32nm or so for many years, this doesn't obey the Moore's Law, they can't make a faster CPU instead they can only make multi-core CPUs.

Can you check this Nfactor: 21      4194304      512MB      1636426656      Tue - 09 Nov 2021 - 02:57:36 GMT

If we can be safe at this year, then we can have another 9 years to upgrade our equipments.

This is for the PoW model, here is another story for PoS.

Tell from the code, PoS uses SHA256, right? Thank god, it doesn't use SCRYPT-JANE this gives me relief, if PoW blocks generation becomes slow, the PoS block can make the network continue functioning.

I'm measuring Nfactor=21 (N=4194304) to yield about 1.73 hashes/sec on a 4 year old dual Xeon E5450 server (combined performance in the ballpark of an i7-2600k).

EDIT - All my benchmarks out through Nfactor=21 are now posted in the table of Nfactor++ events:
https://bt.irlbtc.com/view/206577.msg2162620#msg2162620

It's readily apparent at what point the memory usage becomes high enough to no longer fit in the on-die L1/L2 caches on these particular Xeon CPU's and starts falling to entirely off-chip memory.

^^ Have you tried playing with the lookup gap more? You should still hit faster GPU performance as by 8192 you will have moved off the CPU cache and are writing to RAM (maybe also L3).

Good point! I'll fix my numbers.


I've played with it quite a bit. Also, nothing helped with 8192, it's all invalids.

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:

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.