const runtime.traceEvSpanAlloc

2 uses

	runtime (current package)
		traceallocfree.go#L97: 	tl.eventWriter(traceGoRunning, traceProcRunning).commit(traceEvSpanAlloc, traceSpanID(s), traceArg(s.npages), traceSpanTypeAndClass(s))
		traceexp.go#L56: 	traceEvSpanAlloc // heap span alloc [timestamp, id, npages, type/class]