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v1.18: Scheduler - prioritization fees/cost (solana-labs#34888)
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@apfitzge
apfitzge committed Mar 11, 2024
1 parent 1f79867 commit 1f252c6
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Showing 4 changed files with 110 additions and 163 deletions.
21 changes: 5 additions & 16 deletions core/src/banking_stage/transaction_scheduler/prio_graph_scheduler.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ impl PrioGraphScheduler {
saturating_add_assign!(num_scheduled, 1);

let sanitized_transaction_ttl = transaction_state.transition_to_pending();
let cost = transaction_state.transaction_cost().sum();
let cost = transaction_state.cost();

let SanitizedTransactionTTL {
transaction,
Expand Down Expand Up @@ -490,12 +490,9 @@ mod tests {
crate::banking_stage::consumer::TARGET_NUM_TRANSACTIONS_PER_BATCH,
crossbeam_channel::{unbounded, Receiver},
itertools::Itertools,
solana_cost_model::cost_model::CostModel,
solana_runtime::transaction_priority_details::TransactionPriorityDetails,
solana_sdk::{
compute_budget::ComputeBudgetInstruction, feature_set::FeatureSet, hash::Hash,
message::Message, pubkey::Pubkey, signature::Keypair, signer::Signer,
system_instruction, transaction::Transaction,
compute_budget::ComputeBudgetInstruction, hash::Hash, message::Message, pubkey::Pubkey,
signature::Keypair, signer::Signer, system_instruction, transaction::Transaction,
},
std::borrow::Borrow,
};
Expand Down Expand Up @@ -568,20 +565,12 @@ mod tests {
let id = TransactionId::new(index as u64);
let transaction =
prioritized_tranfers(from_keypair.borrow(), to_pubkeys, lamports, priority);
let transaction_cost = CostModel::calculate_cost(&transaction, &FeatureSet::default());
let transaction_ttl = SanitizedTransactionTTL {
transaction,
max_age_slot: Slot::MAX,
};
container.insert_new_transaction(
id,
transaction_ttl,
TransactionPriorityDetails {
priority,
compute_unit_limit: 1,
},
transaction_cost,
);
const TEST_TRANSACTION_COST: u64 = 5000;
container.insert_new_transaction(id, transaction_ttl, priority, TEST_TRANSACTION_COST);
}

container
Expand Down
83 changes: 67 additions & 16 deletions core/src/banking_stage/transaction_scheduler/scheduler_controller.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,10 +20,12 @@ use {
solana_accounts_db::transaction_error_metrics::TransactionErrorMetrics,
solana_cost_model::cost_model::CostModel,
solana_measure::measure_us,
solana_program_runtime::compute_budget_processor::process_compute_budget_instructions,
solana_runtime::{bank::Bank, bank_forks::BankForks},
solana_sdk::{
clock::MAX_PROCESSING_AGE, saturating_add_assign, timing::AtomicInterval,
transaction::SanitizedTransaction,
clock::MAX_PROCESSING_AGE,
feature_set::include_loaded_accounts_data_size_in_fee_calculation, fee::FeeBudgetLimits,
saturating_add_assign, timing::AtomicInterval, transaction::SanitizedTransaction,
},
std::{
sync::{Arc, RwLock},
Expand Down Expand Up @@ -309,21 +311,24 @@ impl SchedulerController {
let mut error_counts = TransactionErrorMetrics::default();
for chunk in packets.chunks(CHUNK_SIZE) {
let mut post_sanitization_count: usize = 0;
let (transactions, priority_details): (Vec<_>, Vec<_>) = chunk
let (transactions, fee_budget_limits_vec): (Vec<_>, Vec<_>) = chunk
.iter()
.filter_map(|packet| {
packet
.build_sanitized_transaction(feature_set, vote_only, bank.as_ref())
.map(|tx| (tx, packet.priority_details()))
packet.build_sanitized_transaction(feature_set, vote_only, bank.as_ref())
})
.inspect(|_| saturating_add_assign!(post_sanitization_count, 1))
.filter(|(tx, _)| {
.filter(|tx| {
SanitizedTransaction::validate_account_locks(
tx.message(),
transaction_account_lock_limit,
)
.is_ok()
})
.filter_map(|tx| {
process_compute_budget_instructions(tx.message().program_instructions_iter())
.map(|compute_budget| (tx, compute_budget.into()))
.ok()
})
.unzip();

let check_results = bank.check_transactions(
Expand All @@ -335,16 +340,17 @@ impl SchedulerController {
let post_lock_validation_count = transactions.len();

let mut post_transaction_check_count: usize = 0;
for ((transaction, priority_details), _) in transactions
for ((transaction, fee_budget_limits), _) in transactions
.into_iter()
.zip(priority_details)
.zip(fee_budget_limits_vec)
.zip(check_results)
.filter(|(_, check_result)| check_result.0.is_ok())
{
saturating_add_assign!(post_transaction_check_count, 1);
let transaction_id = self.transaction_id_generator.next();

let transaction_cost = CostModel::calculate_cost(&transaction, &bank.feature_set);
let (priority, cost) =
Self::calculate_priority_and_cost(&transaction, &fee_budget_limits, &bank);
let transaction_ttl = SanitizedTransactionTTL {
transaction,
max_age_slot: last_slot_in_epoch,
Expand All @@ -353,8 +359,8 @@ impl SchedulerController {
if self.container.insert_new_transaction(
transaction_id,
transaction_ttl,
priority_details,
transaction_cost,
priority,
cost,
) {
saturating_add_assign!(self.count_metrics.num_dropped_on_capacity, 1);
}
Expand Down Expand Up @@ -382,6 +388,51 @@ impl SchedulerController {
);
}
}

/// Calculate priority and cost for a transaction:
///
/// Cost is calculated through the `CostModel`,
/// and priority is calculated through a formula here that attempts to sell
/// blockspace to the highest bidder.
///
/// The priority is calculated as:
/// P = R / (1 + C)
/// where P is the priority, R is the reward,
/// and C is the cost towards block-limits.
///
/// Current minimum costs are on the order of several hundred,
/// so the denominator is effectively C, and the +1 is simply
/// to avoid any division by zero due to a bug - these costs
/// are calculated by the cost-model and are not direct
/// from user input. They should never be zero.
/// Any difference in the prioritization is negligible for
/// the current transaction costs.
fn calculate_priority_and_cost(
transaction: &SanitizedTransaction,
fee_budget_limits: &FeeBudgetLimits,
bank: &Bank,
) -> (u64, u64) {
let cost = CostModel::calculate_cost(transaction, &bank.feature_set).sum();
let fee = bank.fee_structure.calculate_fee(
transaction.message(),
5_000, // this just needs to be non-zero
fee_budget_limits,
bank.feature_set
.is_active(&include_loaded_accounts_data_size_in_fee_calculation::id()),
);

// We need a multiplier here to avoid rounding down too aggressively.
// For many transactions, the cost will be greater than the fees in terms of raw lamports.
// For the purposes of calculating prioritization, we multiply the fees by a large number so that
// the cost is a small fraction.
// An offset of 1 is used in the denominator to explicitly avoid division by zero.
const MULTIPLIER: u64 = 1_000_000;
(
fee.saturating_mul(MULTIPLIER)
.saturating_div(cost.saturating_add(1)),
cost,
)
}
}

#[derive(Default)]
Expand Down Expand Up @@ -468,7 +519,7 @@ impl SchedulerCountMetrics {
self.num_dropped_on_age_and_status,
i64
),
("num_dropped_on_capacity", self.num_dropped_on_capacity, i64)
("num_dropped_on_capacity", self.num_dropped_on_capacity, i64),
);
}

Expand Down Expand Up @@ -680,7 +731,7 @@ mod tests {
from_keypair: &Keypair,
to_pubkey: &Pubkey,
lamports: u64,
priority: u64,
compute_unit_price: u64,
recent_blockhash: Hash,
) -> Transaction {
// Fund the sending key, so that the transaction does not get filtered by the fee-payer check.
Expand All @@ -695,7 +746,7 @@ mod tests {
}

let transfer = system_instruction::transfer(&from_keypair.pubkey(), to_pubkey, lamports);
let prioritization = ComputeBudgetInstruction::set_compute_unit_price(priority);
let prioritization = ComputeBudgetInstruction::set_compute_unit_price(compute_unit_price);
let message = Message::new(&[transfer, prioritization], Some(&from_keypair.pubkey()));
Transaction::new(&vec![from_keypair], message, recent_blockhash)
}
Expand Down Expand Up @@ -951,7 +1002,7 @@ mod tests {
&Keypair::new(),
&Pubkey::new_unique(),
1,
i,
i * 10,
bank.last_blockhash(),
)
})
Expand Down
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