Make max number of subnet mechanisms configurable

pallets/admin-utils/src/lib.rs

@@ -2186,6 +2186,20 @@ pub mod pallet {
             log::debug!("set_tao_flow_smoothing_factor( {smoothing_factor:?} ) ");
             Ok(())
         }
+
+        /// Sets the global maximum number of mechanisms in a subnet
+        #[pallet::call_index(84)]
+        #[pallet::weight(Weight::from_parts(15_000_000, 0)
+        .saturating_add(<T as frame_system::Config>::DbWeight::get().reads(1_u64))
+        .saturating_add(<T as frame_system::Config>::DbWeight::get().writes(1_u64)))]
+        pub fn sudo_set_max_mechanism_count(
+            origin: OriginFor<T>,
+            max_mechanism_count: MechId,
+        ) -> DispatchResult {
+            ensure_root(origin)?;
+            pallet_subtensor::Pallet::<T>::do_set_max_mechanism_count(max_mechanism_count)?;
+            Ok(())
+        }
     }
 }
 

pallets/subtensor/src/lib.rs

@@ -2041,9 +2041,13 @@ pub mod pallet {
     }
     #[pallet::type_value]
     /// -- ITEM (Maximum number of sub-subnets)
-    pub fn MaxMechanismCount<T: Config>() -> MechId {
+    pub fn DefaultMaxMechanismCount<T: Config>() -> MechId {
         MechId::from(2)
     }
+    #[pallet::storage]
+    /// ITEM( max_mechanism_count )
+    pub type MaxMechanismCount<T> =
+        StorageValue<_, MechId, ValueQuery, DefaultMaxMechanismCount<T>>;
     #[pallet::type_value]
     /// -- ITEM (Rate limit for mechanism count updates)
     pub fn MechanismCountSetRateLimit<T: Config>() -> u64 {

pallets/subtensor/src/subnets/mechanism.rs

@@ -95,7 +95,7 @@ impl<T: Config> Pallet<T> {
         Ok(())
     }
 
-    /// Set the desired valus of sub-subnet count for a subnet identified
+    /// Set the desired value of sub-subnet count for a subnet identified
     /// by netuid
     pub fn do_set_mechanism_count(netuid: NetUid, mechanism_count: MechId) -> DispatchResult {
         // Make sure the subnet exists
@@ -124,6 +124,22 @@ impl<T: Config> Pallet<T> {
         Ok(())
     }
 
+    /// Set the global maximum number of mechanisms per subnet
+    pub fn do_set_max_mechanism_count(max_mechanism_count: MechId) -> DispatchResult {
+        // Max count cannot be zero
+        ensure!(max_mechanism_count > 0.into(), Error::<T>::InvalidValue);
+
+        // Make sure we are not allowing numbers that will break the math
+        ensure!(
+            max_mechanism_count <= MechId::from(MAX_MECHANISM_COUNT_PER_SUBNET),
+            Error::<T>::InvalidValue
+        );
+
+        MaxMechanismCount::<T>::set(max_mechanism_count);
+
+        Ok(())
+    }
+
     /// Update current count for a subnet identified by netuid
     /// - Cleans up all sub-subnet maps if count is reduced
     ///

runtime/src/lib.rs

@@ -220,7 +220,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
     //   `spec_version`, and `authoring_version` are the same between Wasm and native.
     // This value is set to 100 to notify Polkadot-JS App (https://polkadot.js.org/apps) to use
     //   the compatible custom types.
-    spec_version: 338,
+    spec_version: 339,
     impl_version: 1,
     apis: RUNTIME_API_VERSIONS,
     transaction_version: 1,