# Counters and Categories for System Performance

This table contains the values for each category of the counters that measure System performance.

### GROUP NAME: sys

Counter Name | Category | Value
--- | --- | ---
uptime
unit | seconds
description | Number of seconds since system startup.
statistic type | absolute
rollup type | summation
entity | host, virtual machine
resourceCpuUsage
unit | MHz
description | resource CPU usage
statistic type | rate
rollup type | average, minimum, maximum
entity | host, virtual machine
heartbeats
unit | number
description | Number of heartbeats from the virtual machine in the defined interval.
statistic type | delta
rollup type | summation
entity | virtual machine