How to properly use and visualize Start Stop activities in a custom ETW provider

[exelix11]

Context
I'm adding profiling support to an application by emitting ETW events that represent logical function calls.
Currently, after i capture an ETL trace i use a tool to convert it to json for use on speedscope.app, but this produces jsons up to 300MB which does not feel optimal.

The problem
I would like to use something like perfview or Windows Performance Analyzer directly, so i looked into the ETW activity pattern which seems to be meant for this kind of use case, however there is not much documentation.

I tried to follow this reference from ms docs, from what i understand this event pattern should allow perfview to group activities and plot them in a hierarchy view.

Several stackoverflow questions point to the fact that this should be possible, however i couldn't find any working reference code in C.

Repro

I tried writing the following code

#include <stdint.h>
#include <stdbool.h>

#include <windows.h>
#include <winmeta.h>
#include <traceloggingprovider.h>

TRACELOGGING_DEFINE_PROVIDER(
	g_profiler,
	"MyProfiler",
	// Example from https://learn.microsoft.com/it-it/windows/win32/api/traceloggingprovider/nf-traceloggingprovider-tracelogging_define_provider
	// {ce5fa4ea-ab00-5402-8b76-9f76ac858fb5}
	(0xce5fa4ea, 0xab00, 0x5402, 0x8b, 0x76, 0x9f, 0x76, 0xac, 0x85, 0x8f, 0xb5));

void RandomSleep() 
{
	Sleep(10 + rand() % 1000);
}

int main(int argc, char** argv)
{
	if (!SUCCEEDED(TraceLoggingRegister(g_profiler)))
		return -1;
	
	// Expected flamegraph:
	//  inner()         |---------|
	//  outer()  |---------------------| ... repeat

	while (true) {
		GUID outer, inner;
		if (!SUCCEEDED(CoCreateGuid(&outer))) return -2;
		if (!SUCCEEDED(CoCreateGuid(&inner))) return -3;

		printf("> enter outer\n");
		TraceLoggingWriteActivity(
			g_profiler, "Function",
			&outer, NULL,
			TraceLoggingOpcode(WINEVENT_OPCODE_START),
			TraceLoggingString("outer()", "func_name")
		);

		RandomSleep();

		printf(">> enter inner\n");
		TraceLoggingWriteActivity(
			g_profiler, "Function",
			&inner, &outer,
			TraceLoggingOpcode(WINEVENT_OPCODE_START),
			TraceLoggingString("inner()", "func_name")
		);

		RandomSleep();

		printf(">> leave inner\n");
		TraceLoggingWriteActivity(
			g_profiler, "Function",
			&inner, NULL,
			TraceLoggingOpcode(WINEVENT_OPCODE_STOP)
		);

		RandomSleep();

		printf("> leave outer\n");
		TraceLoggingWriteActivity(
			g_profiler, "Function",
			&outer, NULL,
			TraceLoggingOpcode(WINEVENT_OPCODE_STOP)
		);

		RandomSleep();
	}

	return 0;
}

You can build it from Visual Studio or just the command line tools with cl Repro.c Advapi32.lib Ole32.lib (i only tried x64 tools).

Then I start an event collection like this:

And the events are collected properly:

However, when i try to open the stacks view for start-stop activities i get Error: Could not find stack source Any Stacks (with StartStop Activities)

Questions

• Is there a mistake in the code or have I misunderstood the purpose of start stop activities ?
• If not activities, is there a way to plot custom function stacks in perfview ?
• Is there a way to generate flamegraphs from this data ?