Add poh speed check and tick speed calibration (#14292)

core/src/banking_stage.rs

@@ -1088,7 +1088,12 @@ pub fn create_test_recorder(
     poh_recorder.set_bank(&bank);
 
     let poh_recorder = Arc::new(Mutex::new(poh_recorder));
-    let poh_service = PohService::new(poh_recorder.clone(), &poh_config, &exit);
+    let poh_service = PohService::new(
+        poh_recorder.clone(),
+        &poh_config,
+        &exit,
+        bank.ticks_per_slot(),
+    );
 
     (exit, poh_recorder, poh_service, entry_receiver)
 }

core/src/poh_service.rs

@@ -1,7 +1,6 @@
 //! The `poh_service` module implements a service that records the passing of
 //! "ticks", a measure of time in the PoH stream
 use crate::poh_recorder::PohRecorder;
-use solana_sdk::clock::DEFAULT_TICKS_PER_SLOT;
 use solana_sdk::poh_config::PohConfig;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
@@ -25,6 +24,7 @@ impl PohService {
         poh_recorder: Arc<Mutex<PohRecorder>>,
         poh_config: &Arc<PohConfig>,
         poh_exit: &Arc<AtomicBool>,
+        ticks_per_slot: u64,
     ) -> Self {
         let poh_exit_ = poh_exit.clone();
         let poh_config = poh_config.clone();
@@ -49,7 +49,12 @@ impl PohService {
                     if let Some(cores) = core_affinity::get_core_ids() {
                         core_affinity::set_for_current(cores[0]);
                     }
-                    Self::tick_producer(poh_recorder, &poh_exit_);
+                    Self::tick_producer(
+                        poh_recorder,
+                        &poh_exit_,
+                        poh_config.target_tick_duration.as_nanos() as u64,
+                        ticks_per_slot,
+                    );
                 }
                 poh_exit_.store(true, Ordering::Relaxed);
             })
@@ -85,27 +90,48 @@ impl PohService {
         }
     }
 
-    fn tick_producer(poh_recorder: Arc<Mutex<PohRecorder>>, poh_exit: &AtomicBool) {
+    fn tick_producer(
+        poh_recorder: Arc<Mutex<PohRecorder>>,
+        poh_exit: &AtomicBool,
+        target_tick_ns: u64,
+        ticks_per_slot: u64,
+    ) {
+        info!("starting with target ns: {}", target_tick_ns);
         let poh = poh_recorder.lock().unwrap().poh.clone();
         let mut now = Instant::now();
+        let mut last_metric = Instant::now();
         let mut num_ticks = 0;
         let mut num_hashes = 0;
+        let mut total_sleep_us = 0;
         loop {
             num_hashes += NUM_HASHES_PER_BATCH;
             if poh.lock().unwrap().hash(NUM_HASHES_PER_BATCH) {
                 // Lock PohRecorder only for the final hash...
                 poh_recorder.lock().unwrap().tick();
                 num_ticks += 1;
-                if num_ticks >= DEFAULT_TICKS_PER_SLOT * 2 {
+                let elapsed_ns = now.elapsed().as_nanos() as u64;
+                // sleep is not accurate enough to get a predictable time.
+                // Kernel can not schedule the thread for a while.
+                while (now.elapsed().as_nanos() as u64) < target_tick_ns {
+                    std::sync::atomic::spin_loop_hint();
+                }
+                total_sleep_us += (now.elapsed().as_nanos() as u64 - elapsed_ns) / 1000;
+                now = Instant::now();
+
+                if last_metric.elapsed().as_millis() > 1000 {
+                    let elapsed_ms = last_metric.elapsed().as_millis() as u64;
+                    let ms_per_slot = (elapsed_ms * ticks_per_slot) / num_ticks;
                     datapoint_info!(
                         "poh-service",
                         ("ticks", num_ticks as i64, i64),
                         ("hashes", num_hashes as i64, i64),
-                        ("elapsed_ms", now.elapsed().as_millis() as i64, i64),
+                        ("elapsed_ms", ms_per_slot, i64),
+                        ("total_sleep_ms", total_sleep_us / 1000, i64),
                     );
+                    total_sleep_us = 0;
                     num_ticks = 0;
                     num_hashes = 0;
-                    now = Instant::now();
+                    last_metric = Instant::now();
                 }
                 if poh_exit.load(Ordering::Relaxed) {
                     break;
@@ -189,7 +215,7 @@ mod tests {
                     .unwrap()
             };
 
-            let poh_service = PohService::new(poh_recorder.clone(), &poh_config, &exit);
+            let poh_service = PohService::new(poh_recorder.clone(), &poh_config, &exit, 0);
             poh_recorder.lock().unwrap().set_working_bank(working_bank);
 
             // get some events

core/src/validator.rs

@@ -40,6 +40,7 @@ use solana_ledger::{
     blockstore_processor::{self, TransactionStatusSender},
     leader_schedule::FixedSchedule,
     leader_schedule_cache::LeaderScheduleCache,
+    poh::compute_hash_time_ns,
 };
 use solana_measure::measure::Measure;
 use solana_metrics::datapoint_info;
@@ -114,6 +115,7 @@ pub struct ValidatorConfig {
     pub bpf_jit: bool,
     pub send_transaction_retry_ms: u64,
     pub send_transaction_leader_forward_count: u64,
+    pub no_poh_speed_test: bool,
 }
 
 impl Default for ValidatorConfig {
@@ -156,6 +158,7 @@ impl Default for ValidatorConfig {
             bpf_jit: false,
             send_transaction_retry_ms: 2000,
             send_transaction_leader_forward_count: 2,
+            no_poh_speed_test: true,
         }
     }
 }
@@ -531,11 +534,20 @@ impl Validator {
                 (None, None)
             };
 
+        if !config.no_poh_speed_test {
+            check_poh_speed(&genesis_config, None);
+        }
+
         if wait_for_supermajority(config, &bank, &cluster_info, rpc_override_health_check) {
             abort();
         }
 
-        let poh_service = PohService::new(poh_recorder.clone(), &poh_config, &exit);
+        let poh_service = PohService::new(
+            poh_recorder.clone(),
+            &poh_config,
+            &exit,
+            bank.ticks_per_slot(),
+        );
         assert_eq!(
             blockstore.new_shreds_signals.len(),
             1,
@@ -754,6 +766,35 @@ fn active_vote_account_exists_in_bank(bank: &Arc<Bank>, vote_account: &Pubkey) -
     false
 }
 
+fn check_poh_speed(genesis_config: &GenesisConfig, maybe_hash_samples: Option<u64>) {
+    if let Some(hashes_per_tick) = genesis_config.hashes_per_tick() {
+        let ticks_per_slot = genesis_config.ticks_per_slot();
+        let hashes_per_slot = hashes_per_tick * ticks_per_slot;
+
+        let hash_samples = maybe_hash_samples.unwrap_or(hashes_per_slot);
+        let hash_time_ns = compute_hash_time_ns(hash_samples);
+
+        let my_ns_per_slot = (hash_time_ns * hashes_per_slot) / hash_samples;
+        debug!("computed: ns_per_slot: {}", my_ns_per_slot);
+        let target_ns_per_slot = genesis_config.ns_per_slot() as u64;
+        debug!(
+            "cluster ns_per_hash: {}ns ns_per_slot: {}",
+            target_ns_per_slot / hashes_per_slot,
+            target_ns_per_slot
+        );
+        if my_ns_per_slot < target_ns_per_slot {
+            let extra_ns = target_ns_per_slot - my_ns_per_slot;
+            info!("PoH speed check: Will sleep {}ns per slot.", extra_ns);
+        } else {
+            error!(
+                "PoH is slower than cluster target tick rate! mine: {} cluster: {}. If you wish to continue, try --ignore-poh-speed",
+                my_ns_per_slot, target_ns_per_slot,
+            );
+            abort();
+        }
+    }
+}
+
 fn post_process_restored_tower(
     restored_tower: crate::consensus::Result<Tower>,
     validator_identity: &Pubkey,
@@ -1266,6 +1307,8 @@ pub fn is_snapshot_config_invalid(
 mod tests {
     use super::*;
     use solana_ledger::{create_new_tmp_ledger, genesis_utils::create_genesis_config_with_leader};
+    use solana_sdk::genesis_config::create_genesis_config;
+    use solana_sdk::poh_config::PohConfig;
     use std::fs::remove_dir_all;
 
     #[test]
@@ -1384,7 +1427,6 @@ mod tests {
     #[test]
     fn test_wait_for_supermajority() {
         solana_logger::setup();
-        use solana_sdk::genesis_config::create_genesis_config;
         use solana_sdk::hash::hash;
         let node_keypair = Arc::new(Keypair::new());
         let cluster_info = ClusterInfo::new(
@@ -1441,4 +1483,38 @@ mod tests {
         assert!(!is_snapshot_config_invalid(500, 100));
         assert!(!is_snapshot_config_invalid(5, 5));
     }
+
+    #[test]
+    #[should_panic]
+    fn test_poh_speed() {
+        solana_logger::setup();
+        let poh_config = PohConfig {
+            target_tick_duration: Duration::from_millis(solana_sdk::clock::MS_PER_TICK),
+            // make PoH rate really fast to cause the panic condition
+            hashes_per_tick: Some(
+                100 * solana_sdk::clock::DEFAULT_HASHES_PER_SECOND
+                    / solana_sdk::clock::DEFAULT_TICKS_PER_SECOND,
+            ),
+            ..PohConfig::default()
+        };
+        let genesis_config = GenesisConfig {
+            poh_config,
+            ..GenesisConfig::default()
+        };
+        check_poh_speed(&genesis_config, Some(10_000));
+    }
+
+    #[test]
+    fn test_poh_speed_no_hashes_per_tick() {
+        let poh_config = PohConfig {
+            target_tick_duration: Duration::from_millis(solana_sdk::clock::MS_PER_TICK),
+            hashes_per_tick: None,
+            ..PohConfig::default()
+        };
+        let genesis_config = GenesisConfig {
+            poh_config,
+            ..GenesisConfig::default()
+        };
+        check_poh_speed(&genesis_config, Some(10_000));
+    }
 }

ledger/src/poh.rs

@@ -82,18 +82,18 @@ impl Poh {
     }
 }
 
-pub fn compute_hashes_per_tick(duration: Duration, hashes_sample_size: u64) -> u64 {
-    // calculate hash rate with the system under maximum load
-    info!(
-        "Running {} hashes in parallel on all threads...",
-        hashes_sample_size
-    );
+pub fn compute_hash_time_ns(hashes_sample_size: u64) -> u64 {
+    info!("Running {} hashes...", hashes_sample_size);
     let mut v = Hash::default();
     let start = Instant::now();
     for _ in 0..hashes_sample_size {
         v = hash(&v.as_ref());
     }
-    let elapsed = start.elapsed().as_millis() as u64;
+    start.elapsed().as_nanos() as u64
+}
+
+pub fn compute_hashes_per_tick(duration: Duration, hashes_sample_size: u64) -> u64 {
+    let elapsed = compute_hash_time_ns(hashes_sample_size) / (1000 * 1000);
     duration.as_millis() as u64 * hashes_sample_size / elapsed
 }
 

validator/src/main.rs

@@ -1104,6 +1104,11 @@ pub fn main() {
                 .default_value("10000")
                 .help("Milliseconds between printing contact debug from gossip."),
         )
+        .arg(
+            Arg::with_name("no_poh_speed_test")
+                .long("no-poh-speed-test")
+                .help("Skip the check for PoH speed."),
+        )
         .arg(
             Arg::with_name("accounts_hash_interval_slots")
                 .long("accounts-hash-slots")
@@ -1544,6 +1549,7 @@ pub fn main() {
             "rpc_send_transaction_leader_forward_count",
             u64
         ),
+        no_poh_speed_test: matches.is_present("no_poh_speed_test"),
         ..ValidatorConfig::default()
     };