# kern.ipc.sem
Plugin: freebsd.plugin
Module: kern.ipc.sem
## Overview
Collect information about semaphore.
This collector is supported on all platforms.
This collector supports collecting metrics from multiple instances of this integration, including remote instances.
### Default Behavior
#### Auto-Detection
This integration doesn't support auto-detection.
#### Limits
The default configuration for this integration does not impose any limits on data collection.
#### Performance Impact
The default configuration for this integration is not expected to impose a significant performance impact on the system.
## Metrics
Metrics grouped by *scope*.
The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.
### Per kern.ipc.sem instance
These metrics shows counters for semaphores on host.
This scope has no labels.
Metrics:
| Metric | Dimensions | Unit |
|:------|:----------|:----|
| system.ipc_semaphores | semaphores | semaphores |
| system.ipc_semaphore_arrays | arrays | arrays |
## Alerts
The following alerts are available:
| Alert name | On metric | Description |
|:------------|:----------|:------------|
| [ semaphores_used ](https://github.com/netdata/netdata/blob/master/health/health.d/ipc.conf) | system.ipc_semaphores | IPC semaphore utilization |
| [ semaphore_arrays_used ](https://github.com/netdata/netdata/blob/master/health/health.d/ipc.conf) | system.ipc_semaphore_arrays | IPC semaphore arrays utilization |
## Setup
### Prerequisites
No action required.
### Configuration
#### File
The configuration file name for this integration is `netdata.conf`.
Configuration for this specific integration is located in the `[plugin:freebsd]` section within that file.
The file format is a modified INI syntax. The general structure is:
```ini
[section1]
option1 = some value
option2 = some other value
[section2]
option3 = some third value
```
You can edit the configuration file using the `edit-config` script from the
Netdata [config directory](https://github.com/netdata/netdata/blob/master/docs/configure/nodes.md#the-netdata-config-directory).
```bash
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config netdata.conf
```
#### Options
Config options
| Name | Description | Default | Required |
|:----|:-----------|:-------|:--------:|
| kern.ipc.sem | Enable or disable semaphore metrics. | yes | no |