Subnet parameters

In addition to miners and validator code, each subnet has a set of hyperparameters that define how it will interact with the bittensor network.

Full hyperparameter reference

The canonical, current list of subnet hyperparameters (as of the latest chain release). Owner-settable shows whether the subnet owner can change the value themselves (✅ yes) or whether it is sudo only (governance / sudo-controlled). Read the live values for a subnet with btcli sudo get --netuid <N>; owners change the owner-settable ones with btcli sudo set.

Taostats

Each subnet tab lists pertinent hyperparameters:

The full list can be found at: https://taostats.io/settings?subnet=19 (update the subnet number for the specific subnet parameters)

Using CLI

To see the parameters of a subnet, use the btcli su getor btcli s hyperparameters

Here are example parameters from Subnet 15 at the time of writing:

Hyperparameter descriptions

• rho: Defaults to 10. Rho is still stored and reported per subnet, but the current Yuma epoch doesn't read it. It has no effect on emissions or consensus.
• kappa: Defaults to 32767 (0.5). Kappa is the stake majority used for consensus. For each miner, Yuma takes the stake-weighted median of validator weights at the κ point: the highest weight that validators holding at least κ of the active stake agree on. Validator weights above that consensus value are clipped. Only root can change it.
• Immunity Period: This parameter defines the duration during which new neurons are protected from certain network penalties or restrictions. (At 12 s/block, 1000 blocks is ~ 3.3 hours.)
• Min Allowed Weights: The minimum number of UIDs a subnet validator must set weights on, before the subnet validator is allowed to set weights on the blockchain.
• Max Weight Limit: Fixed at 65535 (1.0) on every subnet, so a validator can put its whole weight on one miner. It can't be changed.
• Tempo: Blocks between epochs. New subnets start at 360 (about 72 minutes). The subnet owner can set any value from 360 to 50,400 blocks, at most once per 360 blocks; root can set any value. Changing tempo restarts the epoch cycle.
• min_difficulty / max_difficulty / difficulty: Left over from proof-of-work registration, which has been removed. All neuron registration is burned registration, so these values have no effect.
• weights version: Sets the minimum version of validator code that a validator can use (and still set weights).
• weights rate limit: time (in blocks) that a validator may update weights.
• Registration price (burn, burn_increase_mult, burn_half_life): The cost to register a neuron goes up by burn_increase_mult after every registration and decays every block with a half-life of burn_half_life blocks. It always stays between min_burn and max_burn. adjustment_interval and adjustment_alpha are legacy settings that no longer affect subnet registration price.
• activity_cutoff_factor: Sets the activity cutoff in thousandths of a tempo: cutoff blocks = factor × tempo / 1000. The default of 13,889 gives 5,000 blocks at tempo 360. A validator that hasn't set weights within the cutoff is treated as inactive, and its weights are ignored by consensus. The subnet owner can set it from 1,000 to 50,000 (1 to 50 tempos). The older absolute activity_cutoff value is superseded by the factor.
• registration_allowed: Only root can change this. When registration is off, no one can register a neuron on the subnet, and the subnet receives no tao emission. Its share goes to the other subnets.
• target_regs_per_interval: Legacy on normal subnets: the registration price controls demand, and the only hard limit is max_regs_per_block. The root network still uses it, capping root registrations per root tempo at 3× this value.
• min_burn/max_burn: The floor and ceiling of the neuron registration price (in rao, 1e-9 tao). The right column shows the value in tao.
• serving_rate_limit: Determines how often you can change your node's IP address on the blockchain. Expressed in number of blocks. Applies to both subnet validator and subnet miner nodes. Used when you move your node to a new machine.
• Bonds Moving Avg :
  • The weight given to old bonds in the bond EMA, scaled so 1,000,000 = 1.0 (default 900,000 = 0.9). Each epoch, new bond = (1 − m) × this epoch's bond + m × old bond.
    A high value keeps bonds slow-moving: bonds take many epochs to build, and they also take many epochs to fade after a validator stops setting weights.
    A low value makes bonds follow current weights quickly, in both directions. With liquid alpha enabled, the smoothing factor is set per bond between alpha_low and alpha_high instead.
• Max Validators: The number of validator permits on the subnet, given to the highest-stake hotkeys. New subnets start with 64. Only root can change it.
• Adjustment alpha: Legacy. It no longer affects the subnet registration price; see burn_increase_mult and burn_half_life.
• Commit Reveal Period: Weights are encrypted for this many epochs (tempos) before auto-reveal, to prevent Weight Copying. (Formerly commit_reveal_weights_interval, measured in blocks.)
• Commit Reveal Weights Enabled: Boolean if commit reveal is on or off.
• alpha_high/alpha_low: used in Liquid alpha math. Not related to the alpha token
• Liquid Alpha Enabled: Liquid alpha allows for a Consensus based weights.