//go:linkname newTimer time.newTimer
func newTimer(when, period int64, f func(arg any, seq uintptr, delay int64), arg any, c *hchan) *timeTimer {
	t := new(timeTimer)
	t.timer.init(nil, nil)
	t.trace("new")
	if raceenabled {
		racerelease(unsafe.Pointer(&t.timer))
	}
	if c != nil {
		lockInit(&t.sendLock, lockRankTimerSend)
		t.isChan = true
		c.timer = &t.timer
		if c.dataqsiz == 0 {
			throw("invalid timer channel: no capacity")
		}

	// Update it under gcsema to avoid gctrace getting wrong values.
	work.userForced = trigger.kind == gcTriggerCycle

	trace := traceAcquire()
	if trace.ok() {
		trace.GCStart()
		traceRelease(trace)
	}

	// Check that all Ps have finished deferred mcache flushes.
	for _, p := range allp {
		if fg := p.mcache.flushGen.Load(); fg != mheap_.sweepgen {

			inittrace.bytes += uint64(fullSize)
		}

		if traceAllocFreeEnabled() {
			trace := traceAcquire()
			if trace.ok() {
				trace.HeapObjectAlloc(uintptr(x), typ)
				traceRelease(trace)
			}
		}
	}

	if assistG != nil {
		// Account for internal fragmentation in the assist
		// debt now that we know it.
		//
		// N.B. Use the full size because that's how the rest