A Linux virtual server installed on VMware, both the "CPU Utilization" and "Memory Utilization" monitors every 15 minutes, but check the detail is observed missing data.
In reviewing the dynamic graph for "CPU Utilization", the red box shows the data every 15 minutes, whereas the blue box some polls are lost (see picture CPUUtilization.png).
However in "Memory Utilization " by the same time and same server , data were recorded every 15 minutes without loss (see image MemoryUtilization.png).