From 5f2df0ef78be7b24798d0983c9b962740608f1f4 Mon Sep 17 00:00:00 2001 From: glozow Date: Tue, 29 Jul 2025 13:32:38 -0400 Subject: [PATCH] [miner] lower default -blockmintxfee to 1sat/kvB Back when we implemented coin age priority as a miner policy, miners mempools might admit transactions paying very low fees, but then want to set a higher fee for block inclusion. However, since coin age priority was removed in v0.15, the block assembly policy is solely based on fees, so we do not need to apply minimum feerate rules in multiple places. In fact, the block assembly policy ignoring transactions that are added to the mempool is likely undesirable as we waste resources accepting and storing this transaction. Instead, rely on mempool policy to enforce a minimum entry feerate to the mempool (minrelaytxfee). Set the minimum block feerate to the minimum non-zero amount (1sat/kvB) so it collects everything it finds in mempool into the block. --- src/policy/policy.h | 2 +- src/test/miner_tests.cpp | 4 ++++ test/functional/mining_basic.py | 4 ++-- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/src/policy/policy.h b/src/policy/policy.h index ad787630a45..bccd0866a2e 100644 --- a/src/policy/policy.h +++ b/src/policy/policy.h @@ -29,7 +29,7 @@ static constexpr unsigned int DEFAULT_BLOCK_RESERVED_WEIGHT{8000}; * Setting a lower value is prevented at startup. */ static constexpr unsigned int MINIMUM_BLOCK_RESERVED_WEIGHT{2000}; /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/ -static constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1000}; +static constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1}; /** The maximum weight for transactions we're willing to relay/mine */ static constexpr int32_t MAX_STANDARD_TX_WEIGHT{400000}; /** The minimum non-witness size for transactions we're willing to relay/mine: one larger than 64 */ diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp index 9207f1bfc2c..cf0d103b3c7 100644 --- a/src/test/miner_tests.cpp +++ b/src/test/miner_tests.cpp @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -216,6 +217,9 @@ void MinerTestingSetup::TestPackageSelection(const CScript& scriptPubKey, const tx.vout.resize(2); tx.vout[0].nValue = 5000000000LL - 100000000; tx.vout[1].nValue = 100000000; // 1BTC output + // Increase size to avoid rounding errors: when the feerate is extremely small (i.e. 1sat/kvB), evaluating the fee + // at a smaller transaction size gives us a rounded value of 0. + BulkTransaction(tx, 4000); Txid hashFreeTx2 = tx.GetHash(); AddToMempool(tx_mempool, entry.Fee(0).SpendsCoinbase(true).FromTx(tx)); diff --git a/test/functional/mining_basic.py b/test/functional/mining_basic.py index 6707f4b0b43..4683919d1cc 100755 --- a/test/functional/mining_basic.py +++ b/test/functional/mining_basic.py @@ -55,7 +55,7 @@ MAX_FUTURE_BLOCK_TIME = 2 * 3600 MAX_TIMEWARP = 600 VERSIONBITS_TOP_BITS = 0x20000000 VERSIONBITS_DEPLOYMENT_TESTDUMMY_BIT = 28 -DEFAULT_BLOCK_MIN_TX_FEE = 1000 # default `-blockmintxfee` setting [sat/kvB] +DEFAULT_BLOCK_MIN_TX_FEE = 1 # default `-blockmintxfee` setting [sat/kvB] class MiningTest(BitcoinTestFramework): def set_test_params(self): @@ -144,7 +144,7 @@ class MiningTest(BitcoinTestFramework): node = self.nodes[0] # test default (no parameter), zero and a bunch of arbitrary blockmintxfee rates [sat/kvB] - for blockmintxfee_sat_kvb in (DEFAULT_BLOCK_MIN_TX_FEE, 0, 1, 5, 10, 50, 100, 500, 2500, 5000, 21000, 333333, 2500000): + for blockmintxfee_sat_kvb in (DEFAULT_BLOCK_MIN_TX_FEE, 0, 5, 10, 50, 100, 500, 1000, 2500, 5000, 21000, 333333, 2500000): blockmintxfee_btc_kvb = blockmintxfee_sat_kvb / Decimal(COIN) if blockmintxfee_sat_kvb == DEFAULT_BLOCK_MIN_TX_FEE: self.log.info(f"-> Default -blockmintxfee setting ({blockmintxfee_sat_kvb} sat/kvB)...")