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RandomX Algorithm in XDAG

Requirements:

Install RandomX library

git clone https://github.com/tevador/RandomX.git
cd RandomX
mkdir build && cd build
cmake -DARCH=native ..
make
sudo make install

Enable huge pages

Temporary (until next reboot) reserve huge pages

sudo sysctl -w vm.nr_hugepages=2560

Permanent huge pages reservation

sudo bash -c "echo vm.nr_hugepages=2560 >> /etc/sysctl.conf"

  • A pool using randomx of full mode needs 2560 huge pages

  • A pool using randomx of light mode needs 256 huge pages

  • A miner using randomx hash needs 1280 huge pages

When multiple nodes running on one machine, the huge pages number should be the accumulation of all nodes

Launch parameters (test net):

pool

RandomX light mode:
./xdag -t -randomx l -disable-refresh -f pool.config
RandomX fast mode:
./xdag -t -randomx f -disable-refresh -f pool.config

The pool will switch to randomx algorithm, when fork time frame ( defined by constant in rx_hash.h) coming , automatically.

light mode: slower hash speed and less memory usage (about 0.5GB)

fast mode: faster hash speed and more memory usage (more than 5GB)

miner

before RandomX fork:
./xdag -t -m <MINING_THREAD_NUMBER>  <POOL_ADDRESS>:<POOL_PORT> -a <WALLET_ADDRESS>
after RandomX fork:
./xdag -t -randomx f -m <MINING_THREAD_NUMBER> <POOL_ADDRESS>:<POOL_PORT> -a <WALLET_ADDRESS>

The miner can't change PoW algorithm automatically. So miner must turn on switch '-randomx' after algorithm fork manually.

Windows x64 CPU RandowX Miner
DaggerMiner -cpu  -p <POOL_ADDRESS>:<POOL_PORT> -t <MINING_THREAD_NUMBER> -a <WALLET_ADDRESS>

repository https://github.com/swordlet/DaggerRandomxMiner/tree/RandomX

release https://github.com/swordlet/DaggerRandomxMiner/releases/tag/Pre_0.4.0

miner not support GPU yet.

Algorithm Description:

algorithm seed and fork

  • selecting seed block that (seedBlockHeight + 128) % 4096 == 0
  • using sha256 hash of seed block as new randomx seed
  • changing the seed after time frame (Time frame of (seedBlockHeight + 128)) + 128
  • pool algorithm fork after time frame (Time frame of RANDOMX_FORK_HEIGHT) + 128
  • pre set next switch time and next seed when height % 4096 == 0

mining

  • every 64 Bytes mining task contains: 32 Bytes sha256 hash of mining block without nonce( i.e., without last field) and 32 Bytes randomx seed

  • randomx miner using 32 Bytes sha256 hash of mining block concatenate 32 Bytes nonce as input, searching nonce for minimal randomx hash

  • miner send mined nonce back to pool, pool verify nonce with randomx hash and calculate share payment by difficulty of the randomx hash

hash of block

  • using block's randomx hash to calculate its difficulty when block time is end with 0xffff, otherwise using block's Dsha256 hash
  • using block's Dsha256 hash as its hash value in any other circumstance

Implementations:

constants

in rx_hash.h

#define SEEDHASH_EPOCH_BLOCKS   4096 // period of a randomx seed
#define SEEDHASH_EPOCH_LAG    128 // lag time frames for switch randomx seed

#define SEEDHASH_EPOCH_TESTNET_BLOCKS  64
#define SEEDHASH_EPOCH_TESTNET_LAG    32

// fork seed height, (time frame of RANDOMX_FORK_HEIGHT) + SEEDHASH_EPOCH_LAG = fork time frame
#define RANDOMX_FORK_HEIGHT           1540096 

// (time frame of RANDOMX_TESTNET_FORK_HEIGHT) + SEEDHASH_EPOCH_TESTNET_LAG = test net fork time frame
#define RANDOMX_TESTNET_FORK_HEIGHT   196288 // 196288 % 64 = 0