# Why does % CPU usage on an idle barebones server (with no custom runtime plugin) increase with higher available RAM?

**URL:** <https://forum.heroiclabs.com/t/why-does-cpu-usage-on-an-idle-barebones-server-with-no-custom-runtime-plugin-increase-with-higher-available-ram/2702>\
**Category:** Local Setup\
**Tags:** server-framework\
**Created:** [June 2, 2022, 3:54pm UTC](https://forum.heroiclabs.com/t/why-does-cpu-usage-on-an-idle-barebones-server-with-no-custom-runtime-plugin-increase-with-higher-available-ram/2702 "2022-06-02T15:54:36Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![andre.santiago](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.heroiclabs.com/andre.santiago/32/1225_2.png) [@andre.santiago](https://forum.heroiclabs.com/u/andre.santiago)\
**Post date:** [June 2, 2022, 3:54pm UTC](https://forum.heroiclabs.com/t/why-does-cpu-usage-on-an-idle-barebones-server-with-no-custom-runtime-plugin-increase-with-higher-available-ram/2702/1 "2022-06-02T15:54:36Z")

</div>

I’ve identified that idle CPU usage for a Nakama server with **no custom runtime plugin** varies with the specifications of the machine it’s running on. In this case, I’m focusing on the amount of available RAM.

By idle, I mean with no clients connected, no sessions and no network traffic.

In the image below, I’m showing some Prometheus metrics for 3 Nakama instances: **A** , **B** and **C**. In this example image, **B** and **C** are running on a machine with 1Gb of RAM, while **A** is on a machine with 4GB of RAM. All other specifications are identical.

The metrics are shown per instance, and each time point represents the per-second average rate over the previous 30 seconds, except for the number of sessions. They are, from top to bottom:

- CPU Usage: `process_cpu_seconds_total`
- Number of Memory Allocations: `go_memstats_mallocs_total`
- Number of Goroutines: `go_goroutines`
- Number of Sessions: `nakama_sessions`

While not shown, the amount of bytes received (`nakama_overall_message_recv_bytes`) and sent (`nakama_overall_sent_bytes`) was at 0 B when there were no sessions. I can provide more metrics and/or information if necessary.

In case it might also be relevant, these are the options we’re customizing, with secret or unimportant information redacted:

> **config.yml**
>
> ```yaml
> name: <redacted>
> 
> logger:
> level: <redacted>
> file: <redacted>
> rotation: true
> 
> console:
> port: <redacted>
> username: <redacted>
> password: <redacted>
> 
> metrics:
> prometheus_port: <redacted>
> prefix: <redacted>
> 
> runtime:
> http_key: <redacted>
> path: <redacted>
> env: <redacted>
> 
> socket:
> server_key: <redacted>
> idle_timeout_ms: 3600000
> max_request_size_bytes: 10000000
> max_message_size_bytes: 10000000
> 
> session:
> encryption_key: <redacted>
> refresh_encryption_key: <redacted>
> token_expiry_sec: 3600
> refresh_token_expiry_sec: 604800
> single_socket: true
> single_match: true
> 
> ```

As you can see, the % CPU usage is much higher on **A** compared to the others. This is certainly related to the number of memory allocations per second. Why does this happen? And, if possible, how can this be fine-tuned?

1. Versions: Nakama 3.11, Docker 20.10.15
2. Server Framework Runtime language: no custom runtime

 ![graphana-weird-performance](https://us1.discourse-cdn.com/flex020/uploads/heroiclabs/original/2X/f/f3db278fd77de066b922982cb31146b671d762b8.png)