RED stands for Rate, Errors, and Duration — the three golden signals for monitoring request-driven services. Together, they tell you how much traffic a service handles, how often it fails, and how long requests take.
The RED metrics help you spot performance bottlenecks or failures across all your applications. For example, if the error rate of an application increases, you can assume that these errors will impact the experience of your customers. Once you've identified a potential issue, select a row from the Services page to open the application details page.
The application details page has three tabs:
- Overview — latency, rate, error percentage, Apdex, and key operations
- DB Call Metrics — database call latency and throughput
- External Metrics — outbound HTTP/gRPC call metrics
Application Metrics
The Overview tab displays five metric panels in a dashboard grid:
Latency
Shows P50, P90, and P99 latency percentiles for the selected time range. Use this to understand typical vs worst-case response times.
Rate (ops/s)
Shows the number of operations (requests) per second your application serves over time.
Error Percentage
Shows the percentage of operations that returned errors over time.
Apdex
Application Performance Index (Apdex) scores user satisfaction from 0 (least satisfied) to 1 (most satisfied) based on a configurable latency threshold. The current threshold is displayed next to the chart title (default: 0.5). Click Settings in the top-right corner to change it.
Key Operations
Lists the top operations for your service with P50, P95, P99 latency, number of calls, and error rate. Click any operation to drill into its traces.
The Entry Point Spans toggle filters the Key Operations table to show only spans where the serviceName changes — i.e., the first span when a request enters this service from any upstream service. Switching it on hides internal downstream spans and gives you a concise, high-level view of how external traffic is behaving.
View Magnified Graphs
To magnify any metric graph, click the three-dot menu (⋯) in the top-right corner of the chart and select View. This opens an expanded view of the graph for easier analysis.
Filter Series
Inside the magnified graph, use the Filter Series search bar to locate specific labels and include or exclude them. For example, searching p9 in the latency graph shows only p90 and p99 series. Click Save to persist any changes.
Next Steps
- Database Calls — explore database call latency and throughput broken down by operation. See Database Calls.
- External Calls — see outbound HTTP/gRPC call metrics from your service. See External Calls.
- Traces — drill into individual traces for this service from the Trace Explorer.
- Pre-built Dashboard — import the APM Metrics Dashboard for a ready-made view of application performance metrics.
Get Help
If you need help with the steps in this topic, please reach out to us on SigNoz Community Slack.
If you are a SigNoz Cloud user, please use in product chat support located at the bottom right corner of your SigNoz instance or contact us at cloud-support@signoz.io.
