add comment (#2775)

accounts-db/src/accounts_db.rs

@@ -1233,6 +1233,7 @@ impl AccountStorageEntry {
         }
     }
 
+    /// returns # of accounts remaining in the storage
     fn remove_accounts(
         &self,
         num_bytes: usize,
@@ -8030,11 +8031,13 @@ impl AccountsDb {
                     store.slot(), *slot
                 );
                 if offsets.len() == store.count() {
+                    // all remaining alive accounts in the storage are being removed, so the entire storage/slot is dead
                     store.remove_accounts(store.alive_bytes(), reset_accounts, offsets.len());
                     self.dirty_stores.insert(*slot, store.clone());
                     dead_slots.insert(*slot);
                 }
                 else {
+                    // not all accounts are being removed, so figure out sizes of accounts we are removing and update the alive bytes and alive account count
                     let (_, us) = measure_us!({
                         let mut offsets = offsets.iter().cloned().collect::<Vec<_>>();
                         // sort so offsets are in order. This improves efficiency of loading the accounts.