Graps in the Engine Health report fluctuate:
Why are they not constant?
BLAZEMETER PERFORMANCE TESTING
The fluctuation you see in the Engine Health report is normal, there is no cause for alarm. These graphs go up and down while the test progresses. It has to do with how fast the tested application responds to every request and thus how fast the load generator can fire another hit. As the hits/s vary over time, so do the graphs representing resource usage in the load generator.