mirror of
https://github.com/cloud-hypervisor/cloud-hypervisor.git
synced 2024-11-05 11:31:14 +00:00
43 lines
1.4 KiB
Markdown
43 lines
1.4 KiB
Markdown
# Tracing
|
|
|
|
Cloud Hypervisor has a basic tracing infrastucture, particularly focussed on
|
|
the tracing of the initial VM setup.
|
|
|
|
## Usage
|
|
|
|
To enabling tracing, build with "tracing" feature. When compiled without the
|
|
feature the tracing is compiled out.
|
|
|
|
```bash
|
|
cargo build --features "tracing"
|
|
```
|
|
|
|
And then run Cloud Hypervisor as you wish, the trace will be written to the current directory as `cloud-hypervisor-<pid>.trace`. This is JSON file which you can inspect yourself.
|
|
|
|
Alternatively you can use the provided script in
|
|
`scripts/ch-trace-visualiser.py` to generate an SVG:
|
|
|
|
For example:
|
|
|
|
```bash
|
|
scripts/ch-trace-visualiser.py cloud-hypervisor-39466.trace output.svg
|
|
```
|
|
|
|
## Tracing in the codebase
|
|
|
|
There are existing tracepoints in the code base; extra ones can be added for
|
|
more detailed tracing.
|
|
|
|
The `tracer::trace_scoped!()` macro is used to add the current existing scope
|
|
appears as a block in the trace. Other than providing a useful name for the
|
|
event nothing else is required from the developer.
|
|
|
|
The `tracer::start()` and `tracer::end()` functions are already in place for
|
|
generating traces of the boot. These can be relocated for focus tracing on a
|
|
narrow part of the code base.
|
|
|
|
A `tracer::trace_point!()` macro is also provided for an instantaneous trace
|
|
point however this is not in use in the code base currently nor is handled by
|
|
the visualisation script due to the difficulty in representation in the SVG.
|
|
|