[Bitcoin-development] LevelDB benchmarking

[Mike Hearn]

I switched the transaction database to use the Google LevelDB library,
which is a refactored out part of BigTable.

Here are my results. All tests are done on this hard disk:

  http://wdc.custhelp.com/app/answers/detail/a_id/1409/~/specifications-for-the-500-gb-caviar-blue-and-caviar-se16-serial-ata-drive

which has an average 8.9msec seek time. It is a 6 core Ubuntu machine.

I used -loadblock on a chain with with 185127 blocks in it, so it has
lots of SatoshiDice traffic.

8.9 ms (average) seek time

>> Regular BDB as we have today:
real	96m6.836s
user	49m55.220s
sys	2m29.850s

Throughput usually 4-5MB/sec according to iotop, pauses of 8-10
seconds for “Flushing wallet ...”. 611mb of blkindex.dat

>> BDB without sig checking
Throughput, 12-17mb/sec
real	42m51.508s
user	11m52.700s
sys	2m36.590s

Disabling EC verification halves running time.

>> LevelDB no customized options
(I ran the wrong time command here, hence the different format)
3184.73user 181.02system 51:20.81elapsed 109%CPU (0avgtext+0avgdata
1220096maxresident)k
1104inputs+125851776outputs (293569major+37436202minor)pagefaults 0swaps

So, 50 minutes. Throughput often in range of 20-30mb/sec. 397MB of data files.

>> LevelDB w/ 10 bit per key bloom filter
real	50m52.740s
user	53m38.870s
sys	3m4.990s

424mb of data files

No change.

>> LevelDB w/ 10 bit per key bloom filter + 30mb cache (up from 8mb by default)
real	50m53.054s
user	53m26.910s
sys	3m10.720s

No change. The reason is, signature checking is the bottleneck not IO.

>> LevelDB w/10 bit per key bloom filter, 30mb cache, no sigs
real	12m58.998s
user	11m42.330s
sys	2m5.670s

12 minutes vs 42 minutes for BDB on the same benchmark.


Conclusion: LevelDB is a clear win, taking a sync in the absence of
network delays from 95 minutes to 50, at which point signature
checking becomes the bottleneck. It is nearly 4x as fast when
signature checks are not done (ie, when receiving a block containing
only mempool transactions you already verified).