For LevelDB, how can I get the performance of random writes as same as claimed “official” performance report?

You have 2 million key-value pairs and each key value pair is a total of 120 bytes, so 2 million * 120 bytes = 228 MB of data! Your cache is 640 MB so it's quite possible that all of your data is still in RAM and it never really got to disk. As Kitsune pointed out: your hardware is nowhere near as fast as the one that Google tested with and if Google had the same cache size then that could easily produce 30 times difference.

When you run the same benchmark on completely different hardware you're bound to see some differences.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.