Bump default dbfilesize to 128 MiB

The default max file size for LevelDB is 2 MiB, which results in the
LevelDB compaction code generating ~4 disk cache flushes per second when
syncing with the Bitcoin network.
These disk cache flushes are triggered by fdatasync() syscall issued by the
LevelDB compaction code when reaching the max file size.

If the database is on a HDD this flush rate brings the whole system to a
crawl.
It also results in very slow throughput since 2 MiB * 4 flushes per second
is about 8 MiB / second max throughput, while even an old HDD can pull
100 - 200 MiB / second streaming throughput.

Increase the default db file size for LevelDB to 128 MiB instead so the flush
rate drops to about 1 flush / 2 seconds and the system no longer gets so
sluggish.

The db file size value chosen also matches the MAX_BLOCKFILE_SIZE file
size setting already used by the block storage.
This commit is contained in:
Luke Dashjr 2024-05-08 04:07:48 +00:00
parent 11d641b364
commit e83f30e97c

View File

@ -23,7 +23,7 @@
static const size_t DBWRAPPER_PREALLOC_KEY_SIZE = 64;
static const size_t DBWRAPPER_PREALLOC_VALUE_SIZE = 1024;
static constexpr size_t DEFAULT_DB_FILE_SIZE{2};
static constexpr size_t DEFAULT_DB_FILE_SIZE{128};
//! User-controlled performance and debug options.
struct DBOptions {