gistfile1.txt

1M keys, 4kb values 50% compressible, merge operator was "put"

The "Test" column has the test name, number of threads (t1, t2, t4, t8, t16, t32 for 1,2,4,8,16,32 threads) and s0 means "sync=0".
I don't list results

Notes:
* overwrite and mergerandom have similar ops/sec rates. overwrite is slightly faster and I assume that is because compaction is cheaper
  from not handling merges.

* overwrite and mergerandom reach peak throughput at 1 thread when sync=0.

* for 4kb values updaterandom is slower than overwrite at low concurrency but then slightly faster at high concurrency. This is odd because update random
  does a read with each write. The reads are cheap, from cache, but that is still a lot more work. This looks like RocksDB suffers too much
  from mutex contention during writes and there is more contention in the overwrite test because.

** overwrite has more Stall-time than updaterandom at high concurrency

** overwrite has larger commit groups than updaterandom at high concurrency, check out "writes per batch" below
Cumulative writes: 63M writes, 63M keys, 2948K batches, 21.5 writes per batch, ingest: 242.95 GB, 141.48 MB/s --> updaterandom
Cumulative writes: 57M writes, 57M keys, 2579K batches, 22.1 writes per batch, ingest: 219.15 GB, 126.51 MB/s --> overwrite

** While Stall-time was larger for overwrite than updaterandom at high concurrency, stall counts were larger for updaterandom
Stalls(count): 2658 level0_slowdown, 114 level0_numfiles, 0 memtable_compaction, 0 leveln_slowdown_soft, 132 leveln_slowdown_hard --> updaterandom
Stalls(count): 2401 level0_slowdown, 120 level0_numfiles, 0 memtable_compaction, 0 leveln_slowdown_soft, 119 leveln_slowdown_hard --> overwrite

* for 400b values updaterandom was always slower than overwrite, but for that test the database was much larger than RAM so reads were slower,
  maybe several hundred usecs/read.


ops/sec mb/sec  L0_GB   Sum_GB  W-Amp   W-MB/s  usec/op p50     p75     p99     p99.9   p99.99  Uptime  Stall-time      Stall%  Test
27408   107.6   181.8   882.2   4.8     517.3   36.5    11.8    13.7    184     245     1176    1746    00:12:12.367    42.0    overwrite.t1.s0
28230   110.8   186.7   894.5   4.7     525.5   35.4    38.8    48.5    200     246     1158    1743    00:10:31.412    36.2    overwrite.t2.s0
29169   114.5   192.6   895.5   4.6     524.8   34.3    76.4    205.9   382     546     1189    1747    00:10:31.574    36.2    overwrite.t4.s0
30358   119.2   200.9   902.7   4.4     529.1   32.9    149.2   283.2   715     1271    54456   1747    00:10:36.802    36.4    overwrite.t8.s0
31721   124.5   211.0   917.4   4.3     535.5   31.5    325.4   448.0   1169    1366    485893  1754    00:10:58.957    37.6    overwrite.t16.s0
32206   126.4   216.4   936.3   4.3     540.4   31.1    553.0   693.9   1368    1542    979362  1774    00:10:31.967    35.6    overwrite.t32.s0

ops/sec mb/sec  L0_GB   Sum_GB  W-Amp   W-MB/s  usec/op p50     p75     p99     p99.9   p99.99  Uptime  Stall-time      Stall%  Test
26884   105.5   177.4   843.4   4.7     495.2   37.2    12.7    13.9    190     245     1081    1744    00:11:48.811    40.6    mergerandom.t1.s0
26472   103.9   174.8   847.9   4.8     498.1   37.8    42.7    48.7    200     244     1104    1743    00:10:14.410    35.2    mergerandom.t2.s0
28228   110.8   186.3   862.4   4.6     506.3   35.4    71.6    209.2   388     534     1190    1744    00:10:45.767    37.0    mergerandom.t4.s0
29522   115.9   195.4   873.0   4.4     511.7   33.9    144.4   286.4   757     1252    40750   1747    00:11:6.831     38.2    mergerandom.t8.s0
30689   120.5   203.9   884.5   4.3     516.6   32.6    323.1   457.0   1168    1312    556126  1753    00:11:27.429    39.2    mergerandom.t16.s0
30924   121.4   207.8   897.8   4.3     518.2   32.3    547.9   692.8   1369    1549    1032416 1774    00:11:7.363     37.6    mergerandom.t32.s0

ops/sec mb/sec  L0_GB   Sum_GB  W-Amp   W-MB/s  usec/op p50     p75     p99     p99.9   p99.99  Uptime  Stall-time      Stall%  Test
20745   162.9   136.8   894.5   6.5     526.1   48.2    50.4    57.6    87      115     163     1741    00:00:7.865     0.5     updaterandom.t1.s0
27629   216.9   182.5   952.2   5.2     559.7   36.2    61.5    74.0    240     272     300     1742    00:02:56.202    10.1    updaterandom.t2.s0
30317   238.0   200.1   986.4   4.9     579.1   33.0    89.6    119.8   284     299     1273    1744    00:06:56.287    23.9    updaterandom.t4.s0
32806   257.5   217.0   1009.1  4.6     591.4   30.5    158.3   277.6   544     1276    66708   1747    00:08:11.389    28.1    updaterandom.t8.s0
34489   270.8   228.3   1015.5  4.4     594.5   29.0    297.1   430.5   1125    1388    337439  1749    00:08:53.080    30.5    updaterandom.t16.s0
36032   282.9   239.9   1048.8  4.3     610.9   27.8    561.9   741.7   1378    1596    781947  1758    00:08:48.396    30.1    updaterandom.t32.s0