What does RowSet Compaction Duration means?

[Jason Heo]

Hi.

I'm stuck with performance degradation on compaction happens.

My Duration is "4956.71 milliseconds / second" What does this mean? I can't
figure it out.

Here is the captured image: http://imgur.com/WU9sRRq

When I'm doing bulk indexing on tableA, sometimes compaction happens over
tableB. Is this situation is natural?

Thanks.