address comments

crates/sui-core/src/authority/authority_per_epoch_store.rs

@@ -1280,6 +1280,7 @@ impl AuthorityPerEpochStore {
         if let Err(e) = tx_local_execution_time.try_send((ptb.clone(), timings, total_duration)) {
             // This channel should not overflow, but if it does, don't wait; just log an error
             // and drop the observation.
+            // TODO: add a metric for this.
             warn!("failed to send local execution time to observer: {e}");
         }
     }

crates/sui-core/src/authority/execution_time_estimator.rs

@@ -137,6 +137,7 @@ impl ExecutionTimeObserver {
             // Send a new observation through consensus if our current moving average
             // differs too much from the last one we shared.
             // TODO: Consider only sharing observations for entrypoints with congestion.
+            // TODO: Consider only sharing observations that disagree with consensus estimate.
             let new_average = local_observation.moving_average.get_average();
             if local_observation.last_shared.map_or(true, |last_shared| {
                 let diff = last_shared.abs_diff(new_average);
@@ -156,6 +157,7 @@ impl ExecutionTimeObserver {
                     ExecutionTimeObservation::new(epoch_store.name, to_share),
                 );
                 // TODO: Add metrics for shared observations.
+                // TODO: Add a rate limit on consensus submissions.
                 if let Err(e) = self
                     .consensus_adapter
                     .submit_to_consensus(&[transaction], &epoch_store)

crates/sui-core/src/consensus_validator.rs

@@ -100,6 +100,7 @@ impl SuiTxValidator {
                 }
 
                 ConsensusTransactionKind::ExecutionTimeObservation(obs) => {
+                    // TODO: Use a separate limit for this that may truncate shared observations.
                     if obs.estimates.len()
                         > epoch_store
                             .protocol_config()