- System requirements
- Profiler architecture
- Profiler installation
- Uninstall profiler
- Running the profiler
- Profiler activation
- Welcome screen
- Start profiling
- Profiling overhead
- Snapshots
- Solving performance problems
- CPU profiling
- CPU profiling modes
- CPU sampling
- CPU tracing
- Telemetry
- Call tree - All threads
- Call tree - By thread
- Flame graph
- CPU hot spots
- Method list
- Web and database profiling results
- Callee list view
- Method merged callees view
- Method back traces view
- CPU usage estimation
- What-if: an ability to ignore particular methods or focus on particular methods only
- Wall time and CPU time
- Thread profiling
- Object allocation profiling
- Memory profiling
- Exception profiling
- Telemetry
- Probes: monitor higher level events
- Inspections: automatic recognition of typical problems
- Automatically trigger actions on event
- Automatic deobfuscation
- Summary, automatic deobfuscation
- Filters
- Profiler command line
- Command line tool to control profiling
- Export of profiling results to external formats
- Profiler .NET API
- Profiler HTTP API
- Settings
- Troubleshooting and FAQ
CPU sampling
How CPU sampling works
CPU sampling works by taking periodic stack snapshots of the application's call stack to identify which functions are currently executing. Over time, a pattern emerges as certain functions are seen to be executing more frequently than others. The frequency with which a function appears in the sampled call stacks indicates its relative contribution to the total CPU time. By focusing on the functions that appear most often, developers can pinpoint performance bottlenecks.
It's important to note that because CPU sampling takes periodic stack snapshots, it doesn't capture every method invocation. This means that it can't provide an exact count of how many times a specific method was called. The data is statistical in nature and is meant to give an overall view of where the application spends most of its CPU time.
Advantages
- Lower performance overhead
- Easier data analysis
Disadvantages
- Less detailed than tracing
- May miss short-lived or rare events
Performance overhead
The performance impact of CPU sampling is generally low. It adds some overhead to the application, but the impact is often minimal because the sampling frequency is typically low. It is a lightweight method and is usually suitable for use in production environments. Please read this article if you want to learn more about how to reduce or avoid the impact of the profiler.
Use CPU sampling when you want a lightweight method to identify performance bottlenecks with minimal impact on the application. CPU sampling is suitable for use in production environments or when a high-level overview of the application's performance is sufficient.
Options
You can configure some CPU sampling aspects with the following options.
Measured time
Specify whether CPU or wall time will be measured for profiled methods.
Sampling period
Interval between thread stack samples.