//   longer.
	// This causes more churns in code than I hoped, and sometimes
	// makes the code less readable.

	id := fromContext(ctx).id
	userRegion(id, regionStartCode, regionType)
	defer userRegion(id, regionEndCode, regionType)
	fn()
}

// StartRegion starts a region and returns it.
// The returned Region's [Region.End] method must be called

					stats.regionFingerprint = id
				}
				stats.add(t, r)
				summary[id] = stats
			}
		}
		// Sort regions by PC and name.
		userRegions := make([]regionStats, 0, len(summary))
		for _, stats := range summary {
			userRegions = append(userRegions, stats)
		}
		slices.SortFunc(userRegions, func(a, b regionStats) int {
			if c := cmp.Compare(a.Type, b.Type); c != 0 {
				return c
			}
			return cmp.Compare(a.Frame.PC, b.Frame.PC)

		return "Undetermined"
	case gcNotRunning:
		return "NotRunning"
	case gcRunning:
		return "Running"
	}
	return "Bad"
}

// userRegion represents a unique user region when attached to some gState.
type userRegion struct {
	// name must be a resolved string because the string ID for the same
	// string may change across generations, but we care about checking
	// the value itself.

	mux.HandleFunc("/regionsched", traceviewer.SVGProfileHandlerFunc(pprofByRegion(computePprofSched(), parsed)))

	// Region endpoints.
	mux.HandleFunc("/userregions", UserRegionsHandlerFunc(parsed))
	mux.HandleFunc("/userregion", UserRegionHandlerFunc(parsed))

	// Task endpoints.
	mux.HandleFunc("/usertasks", UserTasksHandlerFunc(parsed))
	mux.HandleFunc("/usertask", UserTaskHandlerFunc(parsed))

// trace_userTaskEnd emits a UserRegionBegin or UserRegionEnd event,
// depending on mode (0 == Begin, 1 == End).
//
// TODO(mknyszek): Just make this two functions.
//
//go:linkname trace_userRegion runtime/trace.userRegion
func trace_userRegion(id, mode uint64, name string) {
	tl := traceAcquire()
	if !tl.ok() {
		// Need to do this check because the caller won't have it.
		return
	}
	var ev traceEv
	switch mode {

	EvUserTaskCreate:    {"UserTaskCreate", 11, true, []string{"taskid", "pid", "typeid"}, []string{"name"}},
	EvUserTaskEnd:       {"UserTaskEnd", 11, true, []string{"taskid"}, nil},
	EvUserRegion:        {"UserRegion", 11, true, []string{"taskid", "mode", "typeid"}, []string{"name"}},
	EvUserLog:           {"UserLog", 11, true, []string{"id", "keyid"}, []string{"category", "message"}},

  unexpectedly slow, or reveal relationships between the data values
  logged in a request and its running time.
</p>
<ul>
<li><a href="/usertasks">User-defined tasks</a></li>
<li><a href="/userregions">User-defined regions</a></li>
</ul>

<h2>Garbage collection metrics</h2>
<ul>
<li><a href="/mmu">Minimum mutator utilization</a></li>
</ul>
<p>