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200 changes: 184 additions & 16 deletions docs/core/diagnostics/dotnet-trace.md
Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@
* Is a cross-platform .NET Core tool.
* Enables the collection of .NET Core traces of a running process without a native profiler.
* Is built on [`EventPipe`](./eventpipe.md) of the .NET Core runtime.
* Delivers the same experience on Windows, Linux, or macOS.
* On Linux, provides additional integration with kernel user_events for native tracing tool compatibility.

## Options

Expand All @@ -55,15 +55,12 @@

Displays the version of the dotnet-trace utility.

- **`--duration`**

How long to run the trace. `--duration 00:00:00:05` will run it for 5 seconds.

## Commands

| Command |
|-----------------------------------------------------------|
| [dotnet-trace collect](#dotnet-trace-collect) |
| [dotnet-trace collect-linux](#dotnet-trace-collect-linux) |
| [dotnet-trace convert](#dotnet-trace-convert) |
| [dotnet-trace ps](#dotnet-trace-ps) |
| [dotnet-trace list-profiles](#dotnet-trace-list-profiles) |
Expand All @@ -76,16 +73,27 @@
### Synopsis

```dotnetcli
dotnet-trace collect [--buffersize <size>] [--clreventlevel <clreventlevel>] [--clrevents <clrevents>]
dotnet-trace collect
[--buffersize <size>]
[--clreventlevel <clreventlevel>]
[--clrevents <clrevents>]
[--dsrouter <ios|ios-sim|android|android-emu>]
[--format <Chromium|NetTrace|Speedscope>] [-h|--help] [--duration dd:hh:mm:ss]
[-n, --name <name>] [--diagnostic-port] [-o|--output <trace-file-path>] [-p|--process-id <pid>]
[--profile <profile-name>] [--providers <list-of-comma-separated-providers>]
[--format <Chromium|NetTrace|Speedscope>]
[-h|--help]
[--duration dd:hh:mm:ss]
[-n, --name <name>]
[--diagnostic-port]
[-o|--output <trace-file-path>]
[-p|--process-id <pid>]
[--profile <profile-name>]
[--providers <list-of-comma-separated-providers>]
[-- <command>] (for target applications running .NET 5 or later)
[--show-child-io] [--resume-runtime]
[--show-child-io]
[--resume-runtime]
[--stopping-event-provider-name <stoppingEventProviderName>]
[--stopping-event-event-name <stoppingEventEventName>]
[--stopping-event-payload-filter <stoppingEventPayloadFilter>]
[--event-filters <list-of-comma-separated-event-filters>]
```

### Options
Expand Down Expand Up @@ -158,7 +166,7 @@

- **`--dsrouter {ios|ios-sim|android|android-emu}**

Starts [dotnet-dsrouter](dotnet-dsrouter.md) and connects to it. Requires [dotnet-dsrouter](dotnet-dsrouter.md) to be installed. Run `dotnet-dsrouter -h` for more information.
Starts [dotnet-dsrouter](dotnet-dsrouter.md) and connects to it. Requires [dotnet-dsrouter](dotnet-dsrouter.md) to be installed. Run `dotnet-dsrouter -h` for more information.

- **`--format {Chromium|NetTrace|Speedscope}`**

Expand Down Expand Up @@ -204,11 +212,11 @@

A named pre-defined set of provider configurations that allows common tracing scenarios to be specified succinctly. The following profiles are available:

| Profile | Description |
|---------|-------------|
|`cpu-sampling`|Useful for tracking CPU usage and general .NET runtime information. This is the default option if no profile or providers are specified.|
|`gc-verbose`|Tracks GC collections and samples object allocations.|
|`gc-collect`|Tracks GC collections only at very low overhead.|
| Profile | Description |
|---------|-------------|
|`cpu-sampling`|Useful for tracking CPU usage and general .NET runtime information. This is the default option if no profile or providers are specified.|
|`gc-verbose`|Tracks GC collections and samples object allocations.|
|`gc-collect`|Tracks GC collections only at very low overhead.|

- **`--providers <list-of-comma-separated-providers>`**

Expand Down Expand Up @@ -249,6 +257,34 @@

A string, parsed as [payload_field_name]:[payload_field_value] pairs separated by commas, that will stop the trace upon hitting an event containing all specified payload pairs. Requires `--stopping-event-provider-name` and `--stopping-event-event-name` to be set. for example, `--stopping-event-provider-name Microsoft-Windows-DotNETRuntime --stopping-event-event-name Method/JittingStarted --stopping-event-payload-filter MethodNameSpace:Program,MethodName:OnButtonClick` to stop the trace upon the first `Method/JittingStarted` event for the method `OnButtonClick` in the `Program` namespace emitted by the `Microsoft-Windows-DotNETRuntime` event provider.

- **`--event-filters <list-of-comma-separated-event-filters>`**

Defines an additional optional filter for each provider's events. When no `--event-filters` is specified for a provider, all events allowed by the provider's keywords and level configuration are collected. Event filters provide additional granular control beyond the keyword/level filtering.

**Format:** `ProviderName:<Enable>:<EventIds>`

Where:
- `ProviderName`: The EventPipe provider name (e.g., `Microsoft-Windows-DotNETRuntime`)
- `Enable` : Boolean value indicating whether EventIds will be enabled or disabled, defaults to false
- `EventIds`: Plus-delimited event IDs to enable or disable, defaults to empty.

**Examples:**
```

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# Scenario: Disable specific events from Microsoft-Windows-DotNETRuntime
--event-filters "Microsoft-Windows-DotNETRuntime:false:1+2+3+4+5+6+7+8+9"

# Scenario: Enable specific events from a provider
--event-filters "Microsoft-Windows-DotNETRuntime:true:80+129+130+250"
# Only events 80, 129, 130, and 250 will be collected from this provider (others are filtered out)

# Scenario: Multiple providers with mixed filtering - some providers have no filters
--providers "Microsoft-Windows-DotNETRuntime:0xFFFFFFFF:5,System.Threading.Tasks.TplEventSource:0xFFFFFFFF:5,MyCustomProvider:0xFFFFFFFF:5"
--event-filters "Microsoft-Windows-DotNETRuntime:false:1+2+3,System.Threading.Tasks.TplEventSource:true:7+8+9"
# Microsoft-Windows-DotNETRuntime: All events EXCEPT 1,2,3 are collected
# System.Threading.Tasks.TplEventSource: ONLY events 7,8,9 are collected
# MyCustomProvider: ALL events are collected (no filter specified - follows provider keywords/level)
```

> [!NOTE]

> - Stopping the trace may take a long time (up to minutes) for large applications. The runtime needs to send over the type cache for all managed code that was captured in the trace.
Expand All @@ -259,6 +295,138 @@

> - When specifying a stopping event through the `--stopping-event-*` options, as the EventStream is being parsed asynchronously, there will be some events that pass through between the time a trace event matching the specified stopping event options is parsed and the EventPipeSession is stopped.

## dotnet-trace collect-linux

Collects diagnostic traces from .NET applications using Linux user_events as a transport layer. This command provides the same functionality as [`dotnet-trace collect`](#dotnet-trace-collect) but routes .NET runtime events through the Linux kernel's user_events subsystem before writing them to `.nettrace` files.

This transport approach enables automatic unification of user-space .NET events with kernel-space system events, since both are captured in the same kernel tracing infrastructure. Linux tools like `perf` and `ftrace` can monitor events in real-time while maintaining full compatibility with existing .NET profiling workflows.

### Prerequisites

- Linux kernel with `CONFIG_USER_EVENTS=y` support (kernel 6.4+)
- Appropriate permissions to access `/sys/kernel/tracing/user_events_data`
- .NET 10+

### Synopsis

```dotnetcli
dotnet-trace collect-linux
[--buffersize <size>]
[--clreventlevel <clreventlevel>]
[--clrevents <clrevents>]
[--format <Chromium|NetTrace|Speedscope>]
[-h|--help]
[--duration dd:hh:mm:ss]
[-n, --name <name>]
[--diagnostic-port]
[-o|--output <trace-file-path>]
[-p|--process-id <pid>]
[--profile <profile-name>]
[--providers <list-of-comma-separated-providers>]
[-- <command>] (for target applications running .NET 10 or later)
[--show-child-io]
[--resume-runtime]
[--stopping-event-provider-name <stoppingEventProviderName>]
[--stopping-event-event-name <stoppingEventEventName>]
[--stopping-event-payload-filter <stoppingEventPayloadFilter>]
[--event-filters <list-of-comma-separated-event-filters>]
[--tracepoint-configs <list-of-comma-separated-tracepoint-configs>]
[--kernel-events <list-of-kernel-events>]
```

### Options

`dotnet-trace collect-linux` supports all the same options as [`dotnet-trace collect`](#dotnet-trace-collect), excluding `--dsrouter`, and additionally offers:

- **`--tracepoint-configs <list-of-comma-separated-tracepoint-configs>` (required)**

Defines the explicit mapping between EventPipe providers and kernel tracepoints. Each provider in `--providers` must have a corresponding entry in `--tracepoint-configs`

**Format:** `ProviderName:<DefaultTracepointName>:<TracepointSets>`

Where:
- `ProviderName`: The EventPipe provider name (e.g., `Microsoft-Windows-DotNETRuntime`)
- `DefaultTracepointName`: Default tracepoint name for this provider (can be empty to require explicit assignment)
- `TracepointSets`: Semi-colon delimited `TracepointName=<EventIds>`
- `EventIds`: Plus-delimited event IDs to route to that tracepoint

> [!NOTE]
> All tracepoint names are automatically prefixed with the provider name to avoid collisions. For example, `gc_events` for the `Microsoft-Windows-DotNETRuntime` provider becomes `Microsoft_Windows_DotNETRuntime_gc_events`.

> [!TIP]
> Use `--event-filters` to disable specific events before they are routed to tracepoints. Event filtering happens before tracepoint routing - only events that pass the filter will be sent to their assigned tracepoints.

**Examples:**
```

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# Scenario: All events from provider go to a default tracepoint
--tracepoint-configs "Microsoft-Windows-DotNETRuntime:dotnet_runtime"
# All enabled events from Microsoft-Windows-DotNETRuntime will be written to Microsoft_Windows_DotNETRuntime_dotnet_runtime

# Scenario: Split events by categories
--tracepoint-configs "Microsoft-Windows-DotNETRuntime::gc_events=1+2+3;jit_events=10+11+12"
# EventIDs 1, 2, and 3 will be written to Microsoft_Windows_DotNETRuntime_gc_events
# EventIDs 10, 11, and 12 will be written to Microsoft_Windows_DotNETRuntime_jit_events

# Multiple providers (comma-separated)
--tracepoint-configs "Microsoft-Windows-DotNETRuntime::gc_events=1+2+3,MyCustomProvider:custom_events"
# EventIds 1, 2, and 3 from Microsoft-Windows-DotNETRuntime will be written to Microsoft_Windows_DotNETRuntime_gc_events
# All enabled events from MyCustomProvider will be written to MyCustomProvider_custom_events
```

- **`--kernel-events <list-of-kernel-events>` (optional)**

A comma-separated list of kernel event categories to include in the trace. These events are automatically grouped into kernel-named tracepoints. Available categories include:

| Category | Description | Linux Tracepoints |
|----------|-------------|-------------------|
| `syscalls` | System call entry/exit events | `syscalls:sys_enter_*`, `syscalls:sys_exit_*` |
| `sched` | Process scheduling events | `sched:sched_switch`, `sched:sched_wakeup` |
| `net` | Network-related events | `net:netif_rx`, `net:net_dev_xmit` |
| `fs` | Filesystem I/O events | `ext4:*`, `vfs:*` |
| `mm` | Memory management events | `kmem:*`, `vmscan:*` |

These events correspond to Linux kernel tracepoints documented in the [Linux kernel tracing documentation](https://www.kernel.org/doc/html/latest/trace/index.html). For more details on available tracepoints, see [ftrace](https://www.kernel.org/doc/html/latest/trace/ftrace.html) and [tracepoints](https://www.kernel.org/doc/html/latest/trace/tracepoints.html).

Example: `--kernel-events syscalls,sched,net`

### Linux Integration

**Tracepoint Configuration Requirements:**

- **Mandatory Mapping**: Every provider must be explicitly mapped to at least a default tracepoint and/or exclusive tracepoint sets via `--tracepoint-configs`
- **Tracepoint Isolation**: Each tracepoint can only receive events from one provider
- **Event Routing**: Different event IDs within a provider can be routed to different tracepoints for granular control
- **Automatic Prefixing**: All tracepoint names are prefixed with the provider name to avoid collisions

**Kernel Integration Points:**

The kernel tracepoints can be accessed through standard Linux tracing interfaces:

- **ftrace**: `/sys/kernel/tracing/events/user_events/`
- **perf**: Use `perf list user_events*` to see available events
- **System monitoring tools**: Any tool that can consume Linux tracepoints

### Examples

```dotnetcli
# All runtime events to one tracepoint
dotnet-trace collect-linux --process-id 1234 \
--providers Microsoft-Windows-DotNETRuntime:0x8000:5 \
--kernel-events syscalls,sched \
--tracepoint-configs "Microsoft-Windows-DotNETRuntime:dotnet_runtime"

# Split runtime events by category
dotnet-trace collect-linux --process-id 1234 \
--providers Microsoft-Windows-DotNETRuntime:0x8001:5 \
--kernel-events syscalls,sched,net,fs \
--tracepoint-configs "Microsoft-Windows-DotNETRuntime::exception_events=80;gc_events=1+2"

# Multiple providers
dotnet-trace collect-linux --process-id 1234 \
--providers "Microsoft-Windows-DotNETRuntime:0x8001:5,MyCustomProvider:0xFFFFFFFF:5" \
--tracepoint-configs "Microsoft-Windows-DotNETRuntime:dotnet_runtime,MyCustomProvider:custom_events"
```

## dotnet-trace convert

Converts `nettrace` traces to alternate formats for use with alternate trace analysis tools.
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -214,7 +214,7 @@ into other formats, such as Chromium or [Speedscope](https://www.speedscope.app/
Trace completed.
```

dotnet-trace uses the [conventional text format](#conventions-for-describing-provider-configuration) for describing provider configuration in
dotnet-trace uses a comma-delimited variant of the [conventional text format](#conventions-for-describing-provider-configuration) for describing provider configuration in
the `--providers` argument. For more options on how to take traces using dotnet-trace, see the
[dotnet-trace docs](./dotnet-trace.md#collect-a-trace-with-dotnet-trace).

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