 # Container CPU usage reported by cadvisor

Let’s take we want to measure CPU usage in containers. cadvisor provides a metric named “container_cpu_usage_seconds_total” which is of a metric type: Counter. As the counter, is an accumulator we need to apply a function over it to see the type of values we need.

I saw in most of the articles, rate function is applied. As we know, the rate function “calculates the per-second average rate of increase of the time series in the range vector”. Actually, the output of rate function query gives us a value that is an average value measure over the period of time.

Example: rate (container_cpu_usage_seconds_total{namespace=“default”}[5m]) gives the average CPU usage in the last 5 mins.
That means, for each instant t in the provided instant vector the rate function uses the values from t - 5m to t to calculate its average value. So, for example, the value at 08:30 describes the average number of “container_cpu_usage_seconds_total” per second that were used between 08:25 and 08:30, the value at 08:31 describes the average number of “container_cpu_usage_seconds_total” per second that were created between 08:26 and 08:31, and so on…

Considering such values to identify the peak CPU usage at instant, as it is an average we might miss the peak spot.

The question here is:

1. Is it not possible to measure the absolute value of “container_cpu_usage_seconds_total”? Ex: What is the absolute current CPU usage at this instance of time?

2. Like, memory metric defined as Gauge “container_memory_usage_bytes”, why “container_cpu_usage_seconds_total” could not be gauge metric type. In this case, we would get the absolute current value of CPU usage. Isn’t? Correct my understanding if I am wrong?

3. In general to dimension an application, is it suggested to take the output of rate function.