Adapt memory usage estimation for flushing

Author: sipa

src/txdb.h

@@ -19,10 +19,8 @@ class CBlockIndex;
 class CCoinsViewDBCursor;
 class uint256;
 
-//! Compensate for extra memory peak (x1.5-x1.9) at flush time.
-static constexpr int DB_PEAK_USAGE_FACTOR = 2;
 //! No need to periodic flush if at least this much space still available.
-static constexpr int MAX_BLOCK_COINSDB_USAGE = 10 * DB_PEAK_USAGE_FACTOR;
+static constexpr int MAX_BLOCK_COINSDB_USAGE = 10;
 //! -dbcache default (MiB)
 static const int64_t nDefaultDbCache = 450;
 //! -dbbatchsize default (bytes)

src/validation.cpp

@@ -1781,7 +1781,7 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
         nLastSetChain = nNow;
     }
     int64_t nMempoolSizeMax = GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
-    int64_t cacheSize = pcoinsTip->DynamicMemoryUsage() * DB_PEAK_USAGE_FACTOR;
+    int64_t cacheSize = pcoinsTip->DynamicMemoryUsage();
     int64_t nTotalSpace = nCoinCacheUsage + std::max<int64_t>(nMempoolSizeMax - nMempoolUsage, 0);
     // The cache is large and we're within 10% and 10 MiB of the limit, but we have time now (not in the middle of a block processing).
     bool fCacheLarge = mode == FLUSH_STATE_PERIODIC && cacheSize > std::max((9 * nTotalSpace) / 10, nTotalSpace - MAX_BLOCK_COINSDB_USAGE * 1024 * 1024);