Difficulty and timestamp in beta


#1

For those interested, timestamp was adjusted 3000 or 4000 seconds forward on blocks 1194 and 1712 with no followup manipulation, and small errors in 3 other timestamps.

About 2.5% took >7.5 minutes after the difficulty stopped its steady rise. About 2.5% took less than 30 seconds. It should have been 5% and 18%, so it's not a Poisson process. I believe the low end is from there being a bare minimum time to solve.

Here's difficulty trend verses block number


#2

That is correct; the internal Equihash solver has a minimum time to find a solution of around 30 seconds.


#3

What hash rate is required to solve in 30 seconds?


#4

That minimum solve time arises out of input data that, through chance, presents a least-challenging sorting process. It's something miners have no control over. What miners can control to improve their individual hashrate is their amount of processing power and memory bandwidth.


#5

On a related topic, how can i determine the network's current hash rate?
Is it the networkhashps in getmininginfo ?
If so, is the rate in the same units you'd get when you do 2 divided by average time to run the "zcbenchmark solveequihash 10" test?


#6

Oh, and how can one generate a graph like that?
The block explorer's got stuck at block 1300-something.


#7

This is a perl script that will parse your debug.log file to get hash IDs as inputs for zcash-cli to get difficulty for your own block explorer. If log2_work in debug.log has some conversion factor to difficulty, it could get by with just the debug file and be a lot faster. Debug.log will include canceled blocks, showing something block explorer doesn't. It's an ugly method, but I didn't know how else to get blocknum, time, and difficulty. Save as a file in the folder above zcash and run with perl filename.

open (F,"<.zcash/testnet3/debug.log"); @a=<F>; close F;

foreach $a (@a) {
   if ($a=~/.+best=([^ ]+).+height=(\d+).+date=\d\d\d\d-\d\d-(\d\d) (\d\d):(\d\d):(\d\d).+/) {
  $block=$2;
  $secs=$3*24*3600+$4*3600+$5*60+$6;
  $info=`./zcash/src/zcash-cli getblock $1`; # 1 is hash
  $info=~m/"difficulty" : (\d+)/sg;  
  $diff=$1;
  $sum=$thissecs;
  $thissecs=$secs-$lastsecs;
  $sum+=$thissecs;
  if ($sum/300 < .22 or $sum/500 > 2.3) { $anomoly=" ***"; }
  $blocks[$block]="$block\t$secs\t$thissecs\t$diff\t$anomoly\n";
  $anomoly="";
  $lastsecs=$secs;
  $check = 'yes';
  }
}
open (F,">difficulty.txt"); print F @blocks; close F;
exit;

To check if the reported timestamps from above are realistic, run the following bash program 24 hr to record when blocks come into your node. https://forum.zcashcommunity.com/t/somebody-already-has-a-gpu-rig/1410/13

Use my code at your own risk.


#8

[deleted, see below]


#9

The script works, give or take some conversion.

About hash rate - if i am getting a block every 30 minutes, then does that mean that i got about 8% of the network power?
Then, by the formula in the benchmark article, the hash rate is difficulty divided by 10, not multiplied by 25.

This is confusing...


#10

Yes, if you're getting a block every 30 minutes, you have 1/12 = 8% network power. From that you should be able to determine relation between difficulty and hashrate, since you know your hash rate per core. Make sure divide equisolve's seconds output for a single core by 2.


#11

[deleted see my next post for better data]


#12

I figured that'd be the case.
I was hoping to run simulations using actual Equihash solving times, but alas, I haven't the time.

It's cool to see posts like this. Keep 'em comin'!


#13

There seem to be 1.1 x Difficulty number of 4-core CPUs on the network (by my measurements of my block solves per total blocks) that can solve in an average of 35 seconds / 2 = 17.5 secs / hash. Divide by 2 because the solver (last I heard) shows the time for 2 solves, not 1. So network hash rate appears to be Diff = 50 gives 50 x 1.1 x 4 x 1/17.5 = 12.5 hashes per second, more like hash rate = D / 4. It seems "benchmark article" (where is it? ) didn't take into account there are 2 hashes per solve, or the solver has been fixed to reflect hashes directly by dividing by two, which would have given me D/8 = hashes per second.


#14

Is the benchmark not working right? I get 15 seconds solves. Is that 2 soles or has it been changed to represent 1?


#15

You misunderstand the sentence you quoted. I said that the time to first solution is around 30s (for the machines I've tested on). I've also said previously that on those same machines, it's about 15s to finish the main solver, and then 15s per solution found. So:

  • 15s to find 0 solutions
  • 30s to find 1 solution
  • 45s to find 2 solutions (but the first one is output from the solver at 30s)
  • etc.

When the solver is reworked as a work queue (#1239) this should drop to around 30s to find all solutions (at least for fewer solutions than available cores).


#16

There continues to be about 3000 seconds added to the timestamp once or twice a day, but no obvious follow-up behavior like before.

The difficulty so far on beta is shown below. This is equal to the number "fast CPUs" on the network. "Fast" means the CPU can get about 38 second voles on the benchmark. This is by observation instead of trying to calculate hashrate.


#17

Note that occasional future timestamps could be due to accidental clock errors. As long as there are not 6 consecutive erroneous timestamps, that would not have any large effect on difficulty (because of the median-of-11 averaging).


#18

It's true that the spacing and size of the timestamp errors (~3600) could have been a single core mining that was 1 hour fast.