sudo_set_kappa
Call v138 → v277, v290 → current #16Sets the kappa parameter for consensus on a subnet .
View calls on chainCall Workflow
This diagram shows the call execution flow: starting with sudo_set_kappa, passing through validation
(signature, nonce, mortality, fee payment), then pre-dispatch checks, followed by dispatch and modifies storage: SubtensorModule.Kappa, and finally post-dispatch where ExtrinsicSuccess is emitted and fees are settled.
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Used by: subnet owners
The Big Picture
Kappa affects how validator weights translate to consensus outcomes. Part of the Yuma consensus parameters.
Use Cases
- Tuning consensus sensitivity
- Adjusting validator influence
From Chain Metadata
The extrinsic sets the kappa for a subnet. It is only callable by the root account or subnet owner. The extrinsic will call the Subtensor pallet to set the kappa.
Input Parameters
Permissions
Origin
Root
Required Role
Requirements
- Caller is root or subnet owner
- Subnet exists
Effects
Storage Modified
Postconditions
- Kappa updated
Side Effects
- Affects consensus weight calculations
Code Examples
import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443
const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);
// Build sudo_set_kappa call (typed, named args)
const netuid = 1;
const kappa = 0;
const tx = api.tx.AdminUtils.sudo_set_kappa({
netuid,
kappa,
});Version History
v138 block 1,907,363 2 args
v290 block 5,947,548 2 args Current
Runtime Info
View Source- Pallet Index
- 19
- Call Index
- 16
- First Version
- v138
- Current Version
- v411