Why there are multi instances when running one single thread application on one core?

[qianlong-zhang]

When I run only one instance Health benchmark from Olden suite on one core, and start logging out the information reaching Memory Controller, there seems to be multi-thread running. For example, when I init one num_requests = 0 and plus one when one more request reaches Memory Controller, the num_requests will not increase linearly. That is, num_requests = 99, 100, 80, 80……

So what's the reason of above situation? is that right?
Thanks.