Configurable hashes per tick

entry/src/poh.rs

@@ -8,7 +8,7 @@ use {
 pub struct Poh {
     pub hash: Hash,
     num_hashes: u64,
-    hashes_per_tick: u64,
+    pub hashes_per_tick: u64,
     remaining_hashes: u64,
     tick_number: u64,
     slot_start_time: Instant,

poh/src/poh_recorder.rs

@@ -225,7 +225,6 @@ pub struct PohRecorder {
     id: Pubkey,
     blockstore: Arc<Blockstore>,
     leader_schedule_cache: Arc<LeaderScheduleCache>,
-    poh_config: PohConfig,
     ticks_per_slot: u64,
     target_ns_per_tick: u64,
     record_lock_contention_us: u64,
@@ -460,13 +459,11 @@ impl PohRecorder {
             ))
     }
 
-    // synchronize PoH with a bank
-    pub fn reset(&mut self, reset_bank: Arc<Bank>, next_leader_slot: Option<(Slot, Slot)>) {
-        self.clear_bank();
+    fn reset_poh(&mut self, reset_bank: Arc<Bank>, reset_start_bank: bool) {
         let blockhash = reset_bank.last_blockhash();
         let poh_hash = {
             let mut poh = self.poh.lock().unwrap();
-            poh.reset(blockhash, self.poh_config.hashes_per_tick);
+            poh.reset(blockhash, *reset_bank.hashes_per_tick());
             poh.hash
         };
         info!(
@@ -479,9 +476,17 @@ impl PohRecorder {
         );
 
         self.tick_cache = vec![];
-        self.start_bank = reset_bank;
+        if reset_start_bank {
+            self.start_bank = reset_bank;
+        }
         self.tick_height = (self.start_slot() + 1) * self.ticks_per_slot;
         self.start_tick_height = self.tick_height + 1;
+    }
+
+    // synchronize PoH with a bank
+    pub fn reset(&mut self, reset_bank: Arc<Bank>, next_leader_slot: Option<(Slot, Slot)>) {
+        self.clear_bank();
+        self.reset_poh(reset_bank, true);
 
         if let Some(ref sender) = self.poh_timing_point_sender {
             // start_slot() is the parent slot. current slot is start_slot() + 1.
@@ -513,6 +518,17 @@ impl PohRecorder {
         };
         trace!("new working bank");
         assert_eq!(working_bank.bank.ticks_per_slot(), self.ticks_per_slot());
+        if let Some(hashes_per_tick) = *working_bank.bank.hashes_per_tick() {
+            if self.poh.lock().unwrap().hashes_per_tick != hashes_per_tick {
+                // Reset poh when changing hashes per tick so that we ensure all ticks
+                // for this slot are created with the proper hashes per tick
+                info!(
+                    "resetting poh due to hashes per tick change detected at {}",
+                    working_bank.bank.slot()
+                );
+                self.reset_poh(working_bank.clone().bank, false);
+            }
+        }
         self.working_bank = Some(working_bank);
 
         // send poh slot start timing point
@@ -865,7 +881,6 @@ impl PohRecorder {
                 leader_schedule_cache: leader_schedule_cache.clone(),
                 ticks_per_slot,
                 target_ns_per_tick,
-                poh_config: poh_config.clone(),
                 record_lock_contention_us: 0,
                 flush_cache_tick_us: 0,
                 flush_cache_no_tick_us: 0,

runtime/src/bank.rs

@@ -108,9 +108,10 @@ use {
         account_utils::StateMut,
         bpf_loader_upgradeable::{self, UpgradeableLoaderState},
         clock::{
-            BankId, Epoch, Slot, SlotCount, SlotIndex, UnixTimestamp, DEFAULT_TICKS_PER_SECOND,
-            INITIAL_RENT_EPOCH, MAX_PROCESSING_AGE, MAX_TRANSACTION_FORWARDING_DELAY,
-            MAX_TRANSACTION_FORWARDING_DELAY_GPU, SECONDS_PER_DAY,
+            BankId, Epoch, Slot, SlotCount, SlotIndex, UnixTimestamp, DEFAULT_HASHES_PER_TICK,
+            DEFAULT_TICKS_PER_SECOND, INITIAL_RENT_EPOCH, MAX_PROCESSING_AGE,
+            MAX_TRANSACTION_FORWARDING_DELAY, MAX_TRANSACTION_FORWARDING_DELAY_GPU,
+            SECONDS_PER_DAY,
         },
         ed25519_program,
         epoch_info::EpochInfo,
@@ -1661,7 +1662,8 @@ impl Bank {
                     let (_, apply_feature_activations_time) = measure!(
                         new.apply_feature_activations(
                             ApplyFeatureActivationsCaller::NewFromParent,
-                            false
+                            false,
+                            vec![false; FeatureActivation::NumVariants as usize],
                         ),
                         "apply_feature_activation",
                     );
@@ -1888,7 +1890,11 @@ impl Bank {
 
         let parent_timestamp = parent.clock().unix_timestamp;
         let mut new = Bank::new_from_parent(parent, collector_id, slot);
-        new.apply_feature_activations(ApplyFeatureActivationsCaller::WarpFromParent, false);
+        new.apply_feature_activations(
+            ApplyFeatureActivationsCaller::WarpFromParent,
+            false,
+            vec![false; FeatureActivation::NumVariants as usize],
+        );
         new.update_epoch_stakes(new.epoch_schedule().get_epoch(slot));
         new.tick_height.store(new.max_tick_height(), Relaxed);
 
@@ -2015,10 +2021,6 @@ impl Bank {
             "Bank snapshot genesis creation time does not match genesis.bin creation time.\
              The snapshot and genesis.bin might pertain to different clusters"
         );
-        assert_eq!(
-            bank.hashes_per_tick,
-            genesis_config.poh_config.hashes_per_tick
-        );
         assert_eq!(bank.ticks_per_slot, genesis_config.ticks_per_slot);
         assert_eq!(
             bank.ns_per_slot,
@@ -6426,6 +6428,7 @@ impl Bank {
         self.apply_feature_activations(
             ApplyFeatureActivationsCaller::FinishInit,
             debug_do_not_add_builtins,
+            vec![false; FeatureActivation::NumVariants as usize],
         );
 
         if self
@@ -7452,10 +7455,12 @@ impl Bank {
 
     // This is called from snapshot restore AND for each epoch boundary
     // The entire code path herein must be idempotent
-    fn apply_feature_activations(
+    pub fn apply_feature_activations(
         &mut self,
         caller: ApplyFeatureActivationsCaller,
         debug_do_not_add_builtins: bool,
+        // This vector is for forcing a feature to get activated for testing purposes
+        features_activated_test: Vec<bool>,
     ) {
         use ApplyFeatureActivationsCaller::*;
         let allow_new_activations = match caller {
@@ -7507,6 +7512,21 @@ impl Bank {
             const ACCOUNTS_DATA_LEN: u64 = 50_000_000_000;
             self.accounts_data_size_initial = ACCOUNTS_DATA_LEN;
         }
+
+        if new_feature_activations.contains(&feature_set::configurable_hashes_per_tick::id())
+            || features_activated_test[FeatureActivation::ConfigurablePohTicksPerSecond as usize]
+        {
+            self.apply_updated_hashes_per_tick(DEFAULT_HASHES_PER_TICK);
+        }
+    }
+
+    fn apply_updated_hashes_per_tick(&mut self, hashes_per_tick: u64) {
+        info!(
+            "Activating configurable_hashes_per_tick {} at slot {}",
+            hashes_per_tick,
+            self.slot(),
+        );
+        self.hashes_per_tick = Some(hashes_per_tick);
     }
 
     fn adjust_sysvar_balance_for_rent(&self, account: &mut AccountSharedData) {
@@ -7797,12 +7817,19 @@ fn calculate_data_size_delta(old_data_size: usize, new_data_size: usize) -> i64
 /// Since `apply_feature_activations()` has different behavior depending on its caller, enumerate
 /// those callers explicitly.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
-enum ApplyFeatureActivationsCaller {
+pub enum ApplyFeatureActivationsCaller {
     FinishInit,
     NewFromParent,
     WarpFromParent,
 }
 
+/// Allows for force enabling feature activations for testing.
+pub enum FeatureActivation {
+    ConfigurablePohTicksPerSecond,
+    // Add new feature activation enums here
+    NumVariants,
+}
+
 /// Return the computed values from `collect_rent_from_accounts()`
 ///
 /// Since `collect_rent_from_accounts()` is running in parallel, instead of updating the
@@ -20157,4 +20184,47 @@ pub(crate) mod tests {
             )),
         );
     }
+
+    #[test]
+    fn test_feature_activation_idempotent() {
+        let GenesisConfigInfo {
+            mut genesis_config, ..
+        } = genesis_utils::create_genesis_config_with_leader(
+            1_000_000 * LAMPORTS_PER_SOL,
+            &Pubkey::new_unique(),
+            100 * LAMPORTS_PER_SOL,
+        );
+        genesis_config.rent = Rent::default();
+        const HASHES_PER_TICK_START: u64 = 3;
+        genesis_config.poh_config.hashes_per_tick = Some(HASHES_PER_TICK_START);
+
+        let mut bank = Bank::new_for_tests(&genesis_config);
+        assert_eq!(bank.hashes_per_tick, Some(HASHES_PER_TICK_START));
+
+        // Don't activate feature
+        let mut test_activation = vec![false; FeatureActivation::NumVariants as usize];
+        bank.apply_feature_activations(
+            ApplyFeatureActivationsCaller::NewFromParent,
+            false,
+            test_activation.clone(),
+        );
+        assert_eq!(bank.hashes_per_tick, Some(HASHES_PER_TICK_START));
+
+        // Activate feature
+        test_activation[FeatureActivation::ConfigurablePohTicksPerSecond as usize] = true;
+        bank.apply_feature_activations(
+            ApplyFeatureActivationsCaller::NewFromParent,
+            false,
+            test_activation.clone(),
+        );
+        assert_eq!(bank.hashes_per_tick, Some(DEFAULT_HASHES_PER_TICK));
+
+        // Activate feature "again"
+        bank.apply_feature_activations(
+            ApplyFeatureActivationsCaller::NewFromParent,
+            false,
+            test_activation,
+        );
+        assert_eq!(bank.hashes_per_tick, Some(DEFAULT_HASHES_PER_TICK));
+    }
 }

sdk/src/feature_set.rs

@@ -554,6 +554,10 @@ pub mod enable_program_redeployment_cooldown {
     solana_sdk::declare_id!("J4HFT8usBxpcF63y46t1upYobJgChmKyZPm5uTBRg25Z");
 }
 
+pub mod configurable_hashes_per_tick {
+    solana_sdk::declare_id!("3uFHb9oKdGfgZGJK9EHaAXN4USvnQtAFC13Fh5gGFS5B");
+}
+
 lazy_static! {
     /// Map of feature identifiers to user-visible description
     pub static ref FEATURE_NAMES: HashMap<Pubkey, &'static str> = [
@@ -687,6 +691,7 @@ lazy_static! {
         (cap_transaction_accounts_data_size::id(), "cap transaction accounts data size up to its compute unit limits #27839"),
         (enable_alt_bn128_syscall::id(), "add alt_bn128 syscalls #27961"),
         (enable_program_redeployment_cooldown::id(), "enable program redeployment cooldown #29135"),
+        (configurable_hashes_per_tick::id(), "Configure desired hashes per tick to update on epoch boundary"),
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()