Esempio n. 1
0
// Called to receive the next queued signal.
// Must only be called from a single goroutine at a time.
//go:linkname signal_recv os/signal.signal_recv
func signal_recv() uint32 {
	for {
		// Serve any signals from local copy.
		for i := uint32(0); i < _NSIG; i++ {
			if sig.recv[i/32]&(1<<(i&31)) != 0 {
				sig.recv[i/32] &^= 1 << (i & 31)
				return i
			}
		}

		// Wait for updates to be available from signal sender.
	Receive:
		for {
			switch atomic.Load(&sig.state) {
			default:
				throw("signal_recv: inconsistent state")
			case sigIdle:
				if atomic.Cas(&sig.state, sigIdle, sigReceiving) {
					notetsleepg(&sig.note, -1)
					noteclear(&sig.note)
					break Receive
				}
			case sigSending:
				if atomic.Cas(&sig.state, sigSending, sigIdle) {
					break Receive
				}
			}
		}

		// Incorporate updates from sender into local copy.
		for i := range sig.mask {
			sig.recv[i] = atomic.Xchg(&sig.mask[i], 0)
		}
	}
}
Esempio n. 2
0
func lock(l *mutex) {
	gp := getg()

	if gp.m.locks < 0 {
		throw("runtime·lock: lock count")
	}
	gp.m.locks++

	// Speculative grab for lock.
	v := atomic.Xchg(key32(&l.key), mutex_locked)
	if v == mutex_unlocked {
		return
	}

	// wait is either MUTEX_LOCKED or MUTEX_SLEEPING
	// depending on whether there is a thread sleeping
	// on this mutex. If we ever change l->key from
	// MUTEX_SLEEPING to some other value, we must be
	// careful to change it back to MUTEX_SLEEPING before
	// returning, to ensure that the sleeping thread gets
	// its wakeup call.
	wait := v

	// On uniprocessors, no point spinning.
	// On multiprocessors, spin for ACTIVE_SPIN attempts.
	spin := 0
	if ncpu > 1 {
		spin = active_spin
	}
	for {
		// Try for lock, spinning.
		for i := 0; i < spin; i++ {
			for l.key == mutex_unlocked {
				if atomic.Cas(key32(&l.key), mutex_unlocked, wait) {
					return
				}
			}
			procyield(active_spin_cnt)
		}

		// Try for lock, rescheduling.
		for i := 0; i < passive_spin; i++ {
			for l.key == mutex_unlocked {
				if atomic.Cas(key32(&l.key), mutex_unlocked, wait) {
					return
				}
			}
			osyield()
		}

		// Sleep.
		v = atomic.Xchg(key32(&l.key), mutex_sleeping)
		if v == mutex_unlocked {
			return
		}
		wait = mutex_sleeping
		futexsleep(key32(&l.key), mutex_sleeping, -1)
	}
}
Esempio n. 3
0
// sweeps one span
// returns number of pages returned to heap, or ^uintptr(0) if there is nothing to sweep
//go:nowritebarrier
func sweepone() uintptr {
	_g_ := getg()

	// increment locks to ensure that the goroutine is not preempted
	// in the middle of sweep thus leaving the span in an inconsistent state for next GC
	_g_.m.locks++
	sg := mheap_.sweepgen
	for {
		idx := atomic.Xadd(&sweep.spanidx, 1) - 1
		if idx >= uint32(len(work.spans)) {
			mheap_.sweepdone = 1
			_g_.m.locks--
			return ^uintptr(0)
		}
		s := work.spans[idx]
		if s.state != mSpanInUse {
			s.sweepgen = sg
			continue
		}
		if s.sweepgen != sg-2 || !atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			continue
		}
		npages := s.npages
		if !s.sweep(false) {
			npages = 0
		}
		_g_.m.locks--
		return npages
	}
}
Esempio n. 4
0
// Sweeps spans in list until reclaims at least npages into heap.
// Returns the actual number of pages reclaimed.
func (h *mheap) reclaimList(list *mSpanList, npages uintptr) uintptr {
	n := uintptr(0)
	sg := mheap_.sweepgen
retry:
	for s := list.first; s != nil; s = s.next {
		if s.sweepgen == sg-2 && atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			list.remove(s)
			// swept spans are at the end of the list
			list.insertBack(s)
			unlock(&h.lock)
			snpages := s.npages
			if s.sweep(false) {
				n += snpages
			}
			lock(&h.lock)
			if n >= npages {
				return n
			}
			// the span could have been moved elsewhere
			goto retry
		}
		if s.sweepgen == sg-1 {
			// the span is being sweept by background sweeper, skip
			continue
		}
		// already swept empty span,
		// all subsequent ones must also be either swept or in process of sweeping
		break
	}
	return n
}
Esempio n. 5
0
File: chan.go Progetto: kraj/gcc
func (q *waitq) dequeue() *sudog {
	for {
		sgp := q.first
		if sgp == nil {
			return nil
		}
		y := sgp.next
		if y == nil {
			q.first = nil
			q.last = nil
		} else {
			y.prev = nil
			q.first = y
			sgp.next = nil // mark as removed (see dequeueSudog)
		}

		// if sgp participates in a select and is already signaled, ignore it
		if sgp.selectdone != nil {
			// claim the right to signal
			if *sgp.selectdone != 0 || !atomic.Cas(sgp.selectdone, 0, 1) {
				continue
			}
		}

		return sgp
	}
}
Esempio n. 6
0
//go:nosplit
func semasleep(ns int64) int32 {
	_g_ := getg()

	// Compute sleep deadline.
	var tsp *timespec
	if ns >= 0 {
		var ts timespec
		var nsec int32
		ns += nanotime()
		ts.set_sec(timediv(ns, 1000000000, &nsec))
		ts.set_nsec(nsec)
		tsp = &ts
	}

	for {
		v := atomic.Load(&_g_.m.waitsemacount)
		if v > 0 {
			if atomic.Cas(&_g_.m.waitsemacount, v, v-1) {
				return 0 // semaphore acquired
			}
			continue
		}

		// Sleep until unparked by semawakeup or timeout.
		ret := lwp_park(tsp, 0, unsafe.Pointer(&_g_.m.waitsemacount), nil)
		if ret == _ETIMEDOUT {
			return -1
		}
	}
}
Esempio n. 7
0
File: chan.go Progetto: w-vi/talks
// Dequeue the `sudog` from the waiters linked list
func (q *waitq) dequeue() *sudog {
	for {
		sgp := q.first
		if sgp == nil {
			return nil
		}
		y := sgp.next
		if y == nil {
			q.first = nil
			q.last = nil
		} else {
			y.prev = nil
			q.first = y
			sgp.next = nil // mark as removed (see dequeueSudog)
		}

		if sgp.selectdone != nil {
			if *sgp.selectdone != 0 || !atomic.Cas(sgp.selectdone, 0, 1) {
				continue
			}
		}

		return sgp
	}
}
Esempio n. 8
0
// sweeps one span
// returns number of pages returned to heap, or ^uintptr(0) if there is nothing to sweep
//go:nowritebarrier
func sweepone() uintptr {
	_g_ := getg()

	// increment locks to ensure that the goroutine is not preempted
	// in the middle of sweep thus leaving the span in an inconsistent state for next GC
	_g_.m.locks++
	sg := mheap_.sweepgen
	for {
		idx := atomic.Xadd(&sweep.spanidx, 1) - 1
		if idx >= uint32(len(work.spans)) {
			mheap_.sweepdone = 1
			_g_.m.locks--
			if debug.gcpacertrace > 0 && idx == uint32(len(work.spans)) {
				print("pacer: sweep done at heap size ", memstats.heap_live>>20, "MB; allocated ", mheap_.spanBytesAlloc>>20, "MB of spans; swept ", mheap_.pagesSwept, " pages at ", mheap_.sweepPagesPerByte, " pages/byte\n")
			}
			return ^uintptr(0)
		}
		s := work.spans[idx]
		if s.state != mSpanInUse {
			s.sweepgen = sg
			continue
		}
		if s.sweepgen != sg-2 || !atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			continue
		}
		npages := s.npages
		if !s.sweep(false) {
			npages = 0
		}
		_g_.m.locks--
		return npages
	}
}
Esempio n. 9
0
// gcLockStackBarriers synchronizes with tracebacks of gp's stack
// during sigprof for installation or removal of stack barriers. It
// blocks until any current sigprof is done tracebacking gp's stack
// and then disallows profiling tracebacks of gp's stack.
//
// This is necessary because a sigprof during barrier installation or
// removal could observe inconsistencies between the stkbar array and
// the stack itself and crash.
//
//go:nosplit
func gcLockStackBarriers(gp *g) {
	// Disable preemption so scanstack cannot run while the caller
	// is manipulating the stack barriers.
	acquirem()
	for !atomic.Cas(&gp.stackLock, 0, 1) {
		osyield()
	}
}
Esempio n. 10
0
//go:nosplit
func gcTryLockStackBarriers(gp *g) bool {
	mp := acquirem()
	result := atomic.Cas(&gp.stackLock, 0, 1)
	if !result {
		releasem(mp)
	}
	return result
}
Esempio n. 11
0
File: sema.go Progetto: danny8002/go
func cansemacquire(addr *uint32) bool {
	for {
		v := atomic.Load(addr)
		if v == 0 {
			return false
		}
		if atomic.Cas(addr, v, v-1) {
			return true
		}
	}
}
Esempio n. 12
0
File: proc.go Progetto: kraj/gcc
// If asked to move to or from a Gscanstatus this will throw. Use the castogscanstatus
// and casfrom_Gscanstatus instead.
// casgstatus will loop if the g->atomicstatus is in a Gscan status until the routine that
// put it in the Gscan state is finished.
//go:nosplit
func casgstatus(gp *g, oldval, newval uint32) {
	if (oldval&_Gscan != 0) || (newval&_Gscan != 0) || oldval == newval {
		systemstack(func() {
			print("runtime: casgstatus: oldval=", hex(oldval), " newval=", hex(newval), "\n")
			throw("casgstatus: bad incoming values")
		})
	}

	if oldval == _Grunning && gp.gcscanvalid {
		// If oldvall == _Grunning, then the actual status must be
		// _Grunning or _Grunning|_Gscan; either way,
		// we own gp.gcscanvalid, so it's safe to read.
		// gp.gcscanvalid must not be true when we are running.
		print("runtime: casgstatus ", hex(oldval), "->", hex(newval), " gp.status=", hex(gp.atomicstatus), " gp.gcscanvalid=true\n")
		throw("casgstatus")
	}

	// See http://golang.org/cl/21503 for justification of the yield delay.
	const yieldDelay = 5 * 1000
	var nextYield int64

	// loop if gp->atomicstatus is in a scan state giving
	// GC time to finish and change the state to oldval.
	for i := 0; !atomic.Cas(&gp.atomicstatus, oldval, newval); i++ {
		if oldval == _Gwaiting && gp.atomicstatus == _Grunnable {
			systemstack(func() {
				throw("casgstatus: waiting for Gwaiting but is Grunnable")
			})
		}
		// Help GC if needed.
		// if gp.preemptscan && !gp.gcworkdone && (oldval == _Grunning || oldval == _Gsyscall) {
		// 	gp.preemptscan = false
		// 	systemstack(func() {
		// 		gcphasework(gp)
		// 	})
		// }
		// But meanwhile just yield.
		if i == 0 {
			nextYield = nanotime() + yieldDelay
		}
		if nanotime() < nextYield {
			for x := 0; x < 10 && gp.atomicstatus != oldval; x++ {
				procyield(1)
			}
		} else {
			osyield()
			nextYield = nanotime() + yieldDelay/2
		}
	}
	if newval == _Grunning && gp.gcscanvalid {
		// Run queueRescan on the system stack so it has more space.
		systemstack(func() { queueRescan(gp) })
	}
}
Esempio n. 13
0
// sweeps one span
// returns number of pages returned to heap, or ^uintptr(0) if there is nothing to sweep
//go:nowritebarrier
func sweepone() uintptr {
	_g_ := getg()

	// increment locks to ensure that the goroutine is not preempted
	// in the middle of sweep thus leaving the span in an inconsistent state for next GC
	_g_.m.locks++
	sg := mheap_.sweepgen
	for {
		s := mheap_.sweepSpans[1-sg/2%2].pop()
		if s == nil {
			mheap_.sweepdone = 1
			_g_.m.locks--
			if debug.gcpacertrace > 0 && atomic.Cas(&sweep.pacertracegen, sg-2, sg) {
				print("pacer: sweep done at heap size ", memstats.heap_live>>20, "MB; allocated ", mheap_.spanBytesAlloc>>20, "MB of spans; swept ", mheap_.pagesSwept, " pages at ", mheap_.sweepPagesPerByte, " pages/byte\n")
			}
			return ^uintptr(0)
		}
		if s.state != mSpanInUse {
			// This can happen if direct sweeping already
			// swept this span, but in that case the sweep
			// generation should always be up-to-date.
			if s.sweepgen != sg {
				print("runtime: bad span s.state=", s.state, " s.sweepgen=", s.sweepgen, " sweepgen=", sg, "\n")
				throw("non in-use span in unswept list")
			}
			continue
		}
		if s.sweepgen != sg-2 || !atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			continue
		}
		npages := s.npages
		if !s.sweep(false) {
			// Span is still in-use, so this returned no
			// pages to the heap and the span needs to
			// move to the swept in-use list.
			npages = 0
		}
		_g_.m.locks--
		return npages
	}
}
Esempio n. 14
0
// Called from sighandler to send a signal back out of the signal handling thread.
// Reports whether the signal was sent. If not, the caller typically crashes the program.
func sigsend(s uint32) bool {
	bit := uint32(1) << uint(s&31)
	if !sig.inuse || s >= uint32(32*len(sig.wanted)) || sig.wanted[s/32]&bit == 0 {
		return false
	}

	// Add signal to outgoing queue.
	for {
		mask := sig.mask[s/32]
		if mask&bit != 0 {
			return true // signal already in queue
		}
		if atomic.Cas(&sig.mask[s/32], mask, mask|bit) {
			break
		}
	}

	// Notify receiver that queue has new bit.
Send:
	for {
		switch atomic.Load(&sig.state) {
		default:
			throw("sigsend: inconsistent state")
		case sigIdle:
			if atomic.Cas(&sig.state, sigIdle, sigSending) {
				break Send
			}
		case sigSending:
			// notification already pending
			break Send
		case sigReceiving:
			if atomic.Cas(&sig.state, sigReceiving, sigIdle) {
				notewakeup(&sig.note)
				break Send
			}
		}
	}

	return true
}
Esempio n. 15
0
func goexitsall(status *byte) {
	var buf [_ERRMAX]byte
	if !atomic.Cas(&exiting, 0, 1) {
		return
	}
	getg().m.locks++
	n := copy(buf[:], goexits)
	n = copy(buf[n:], gostringnocopy(status))
	pid := getpid()
	for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
		if mp.procid != 0 && mp.procid != pid {
			postnote(mp.procid, buf[:])
		}
	}
	getg().m.locks--
}
Esempio n. 16
0
// flushlog tries to flush the current log and switch to the other one.
// flushlog is called from evict, called from add, called from the signal handler,
// so it cannot allocate memory or block. It can try to swap logs with
// the writing goroutine, as explained in the comment at the top of this file.
//go:nowritebarrierrec
func (p *cpuProfile) flushlog() bool {
	if !atomic.Cas(&p.handoff, 0, uint32(p.nlog)) {
		return false
	}
	notewakeup(&p.wait)

	p.toggle = 1 - p.toggle
	log := &p.log[p.toggle]
	q := 0
	if p.lost > 0 {
		lostPC := funcPC(lostProfileData)
		log[0] = p.lost
		log[1] = 1
		log[2] = lostPC
		q = 3
		p.lost = 0
	}
	p.nlog = q
	return true
}
Esempio n. 17
0
// Returns only when span s has been swept.
//go:nowritebarrier
func (s *mspan) ensureSwept() {
	// Caller must disable preemption.
	// Otherwise when this function returns the span can become unswept again
	// (if GC is triggered on another goroutine).
	_g_ := getg()
	if _g_.m.locks == 0 && _g_.m.mallocing == 0 && _g_ != _g_.m.g0 {
		throw("MSpan_EnsureSwept: m is not locked")
	}

	sg := mheap_.sweepgen
	if atomic.Load(&s.sweepgen) == sg {
		return
	}
	// The caller must be sure that the span is a MSpanInUse span.
	if atomic.Cas(&s.sweepgen, sg-2, sg-1) {
		s.sweep(false)
		return
	}
	// unfortunate condition, and we don't have efficient means to wait
	for atomic.Load(&s.sweepgen) != sg {
		osyield()
	}
}
Esempio n. 18
0
//go:nosplit
func semasleep(ns int64) int32 {
	_g_ := getg()

	// Compute sleep deadline.
	var tsp *timespec
	if ns >= 0 {
		var ts timespec
		var nsec int32
		ns += nanotime()
		ts.set_sec(int64(timediv(ns, 1000000000, &nsec)))
		ts.set_nsec(nsec)
		tsp = &ts
	}

	for {
		v := atomic.Load(&_g_.m.waitsemacount)
		if v > 0 {
			if atomic.Cas(&_g_.m.waitsemacount, v, v-1) {
				return 0 // semaphore acquired
			}
			continue
		}

		// Sleep until woken by semawakeup or timeout; or abort if waitsemacount != 0.
		//
		// From OpenBSD's __thrsleep(2) manual:
		// "The abort argument, if not NULL, points to an int that will
		// be examined [...] immediately before blocking. If that int
		// is non-zero then __thrsleep() will immediately return EINTR
		// without blocking."
		ret := thrsleep(uintptr(unsafe.Pointer(&_g_.m.waitsemacount)), _CLOCK_MONOTONIC, tsp, 0, &_g_.m.waitsemacount)
		if ret == _EWOULDBLOCK {
			return -1
		}
	}
}
Esempio n. 19
0
File: mcentral.go Progetto: gmwu/go
// Allocate a span to use in an MCache.
func (c *mcentral) cacheSpan() *mspan {
	// Deduct credit for this span allocation and sweep if necessary.
	deductSweepCredit(uintptr(class_to_size[c.sizeclass]), 0)

	lock(&c.lock)
	sg := mheap_.sweepgen
retry:
	var s *mspan
	for s = c.nonempty.first; s != nil; s = s.next {
		if s.sweepgen == sg-2 && atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			c.nonempty.remove(s)
			c.empty.insertBack(s)
			unlock(&c.lock)
			s.sweep(true)
			goto havespan
		}
		if s.sweepgen == sg-1 {
			// the span is being swept by background sweeper, skip
			continue
		}
		// we have a nonempty span that does not require sweeping, allocate from it
		c.nonempty.remove(s)
		c.empty.insertBack(s)
		unlock(&c.lock)
		goto havespan
	}

	for s = c.empty.first; s != nil; s = s.next {
		if s.sweepgen == sg-2 && atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			// we have an empty span that requires sweeping,
			// sweep it and see if we can free some space in it
			c.empty.remove(s)
			// swept spans are at the end of the list
			c.empty.insertBack(s)
			unlock(&c.lock)
			s.sweep(true)
			if s.freelist.ptr() != nil {
				goto havespan
			}
			lock(&c.lock)
			// the span is still empty after sweep
			// it is already in the empty list, so just retry
			goto retry
		}
		if s.sweepgen == sg-1 {
			// the span is being swept by background sweeper, skip
			continue
		}
		// already swept empty span,
		// all subsequent ones must also be either swept or in process of sweeping
		break
	}
	unlock(&c.lock)

	// Replenish central list if empty.
	s = c.grow()
	if s == nil {
		return nil
	}
	lock(&c.lock)
	c.empty.insertBack(s)
	unlock(&c.lock)

	// At this point s is a non-empty span, queued at the end of the empty list,
	// c is unlocked.
havespan:
	cap := int32((s.npages << _PageShift) / s.elemsize)
	n := cap - int32(s.ref)
	if n == 0 {
		throw("empty span")
	}
	usedBytes := uintptr(s.ref) * s.elemsize
	if usedBytes > 0 {
		reimburseSweepCredit(usedBytes)
	}
	if s.freelist.ptr() == nil {
		throw("freelist empty")
	}
	s.incache = true
	return s
}
Esempio n. 20
0
func check() {
	var (
		a     int8
		b     uint8
		c     int16
		d     uint16
		e     int32
		f     uint32
		g     int64
		h     uint64
		i, i1 float32
		j, j1 float64
		k, k1 unsafe.Pointer
		l     *uint16
		m     [4]byte
	)
	type x1t struct {
		x uint8
	}
	type y1t struct {
		x1 x1t
		y  uint8
	}
	var x1 x1t
	var y1 y1t

	if unsafe.Sizeof(a) != 1 {
		throw("bad a")
	}
	if unsafe.Sizeof(b) != 1 {
		throw("bad b")
	}
	if unsafe.Sizeof(c) != 2 {
		throw("bad c")
	}
	if unsafe.Sizeof(d) != 2 {
		throw("bad d")
	}
	if unsafe.Sizeof(e) != 4 {
		throw("bad e")
	}
	if unsafe.Sizeof(f) != 4 {
		throw("bad f")
	}
	if unsafe.Sizeof(g) != 8 {
		throw("bad g")
	}
	if unsafe.Sizeof(h) != 8 {
		throw("bad h")
	}
	if unsafe.Sizeof(i) != 4 {
		throw("bad i")
	}
	if unsafe.Sizeof(j) != 8 {
		throw("bad j")
	}
	if unsafe.Sizeof(k) != sys.PtrSize {
		throw("bad k")
	}
	if unsafe.Sizeof(l) != sys.PtrSize {
		throw("bad l")
	}
	if unsafe.Sizeof(x1) != 1 {
		throw("bad unsafe.Sizeof x1")
	}
	if unsafe.Offsetof(y1.y) != 1 {
		throw("bad offsetof y1.y")
	}
	if unsafe.Sizeof(y1) != 2 {
		throw("bad unsafe.Sizeof y1")
	}

	if timediv(12345*1000000000+54321, 1000000000, &e) != 12345 || e != 54321 {
		throw("bad timediv")
	}

	var z uint32
	z = 1
	if !atomic.Cas(&z, 1, 2) {
		throw("cas1")
	}
	if z != 2 {
		throw("cas2")
	}

	z = 4
	if atomic.Cas(&z, 5, 6) {
		throw("cas3")
	}
	if z != 4 {
		throw("cas4")
	}

	z = 0xffffffff
	if !atomic.Cas(&z, 0xffffffff, 0xfffffffe) {
		throw("cas5")
	}
	if z != 0xfffffffe {
		throw("cas6")
	}

	k = unsafe.Pointer(uintptr(0xfedcb123))
	if sys.PtrSize == 8 {
		k = unsafe.Pointer(uintptr(k) << 10)
	}
	if casp(&k, nil, nil) {
		throw("casp1")
	}
	k1 = add(k, 1)
	if !casp(&k, k, k1) {
		throw("casp2")
	}
	if k != k1 {
		throw("casp3")
	}

	m = [4]byte{1, 1, 1, 1}
	atomic.Or8(&m[1], 0xf0)
	if m[0] != 1 || m[1] != 0xf1 || m[2] != 1 || m[3] != 1 {
		throw("atomicor8")
	}

	*(*uint64)(unsafe.Pointer(&j)) = ^uint64(0)
	if j == j {
		throw("float64nan")
	}
	if !(j != j) {
		throw("float64nan1")
	}

	*(*uint64)(unsafe.Pointer(&j1)) = ^uint64(1)
	if j == j1 {
		throw("float64nan2")
	}
	if !(j != j1) {
		throw("float64nan3")
	}

	*(*uint32)(unsafe.Pointer(&i)) = ^uint32(0)
	if i == i {
		throw("float32nan")
	}
	if i == i {
		throw("float32nan1")
	}

	*(*uint32)(unsafe.Pointer(&i1)) = ^uint32(1)
	if i == i1 {
		throw("float32nan2")
	}
	if i == i1 {
		throw("float32nan3")
	}

	testAtomic64()

	if _FixedStack != round2(_FixedStack) {
		throw("FixedStack is not power-of-2")
	}

	if !checkASM() {
		throw("assembly checks failed")
	}
}
Esempio n. 21
0
File: runtime1.go Progetto: kraj/gcc
func check() {

	// This doesn't currently work for gccgo.  Because escape
	// analysis is not turned on by default, the code below that
	// takes the address of local variables causes memory
	// allocation, but this function is called before the memory
	// allocator has been initialized.
	return

	var (
		a     int8
		b     uint8
		c     int16
		d     uint16
		e     int32
		f     uint32
		g     int64
		h     uint64
		i, i1 float32
		j, j1 float64
		k, k1 unsafe.Pointer
		l     *uint16
		m     [4]byte
	)
	type x1t struct {
		x uint8
	}
	type y1t struct {
		x1 x1t
		y  uint8
	}
	var x1 x1t
	var y1 y1t

	if unsafe.Sizeof(a) != 1 {
		throw("bad a")
	}
	if unsafe.Sizeof(b) != 1 {
		throw("bad b")
	}
	if unsafe.Sizeof(c) != 2 {
		throw("bad c")
	}
	if unsafe.Sizeof(d) != 2 {
		throw("bad d")
	}
	if unsafe.Sizeof(e) != 4 {
		throw("bad e")
	}
	if unsafe.Sizeof(f) != 4 {
		throw("bad f")
	}
	if unsafe.Sizeof(g) != 8 {
		throw("bad g")
	}
	if unsafe.Sizeof(h) != 8 {
		throw("bad h")
	}
	if unsafe.Sizeof(i) != 4 {
		throw("bad i")
	}
	if unsafe.Sizeof(j) != 8 {
		throw("bad j")
	}
	if unsafe.Sizeof(k) != sys.PtrSize {
		throw("bad k")
	}
	if unsafe.Sizeof(l) != sys.PtrSize {
		throw("bad l")
	}
	if unsafe.Sizeof(x1) != 1 {
		throw("bad unsafe.Sizeof x1")
	}
	if unsafe.Offsetof(y1.y) != 1 {
		throw("bad offsetof y1.y")
	}
	if unsafe.Sizeof(y1) != 2 {
		throw("bad unsafe.Sizeof y1")
	}

	if timediv(12345*1000000000+54321, 1000000000, &e) != 12345 || e != 54321 {
		throw("bad timediv")
	}

	var z uint32
	z = 1
	if !atomic.Cas(&z, 1, 2) {
		throw("cas1")
	}
	if z != 2 {
		throw("cas2")
	}

	z = 4
	if atomic.Cas(&z, 5, 6) {
		throw("cas3")
	}
	if z != 4 {
		throw("cas4")
	}

	z = 0xffffffff
	if !atomic.Cas(&z, 0xffffffff, 0xfffffffe) {
		throw("cas5")
	}
	if z != 0xfffffffe {
		throw("cas6")
	}

	k = unsafe.Pointer(uintptr(0xfedcb123))
	if sys.PtrSize == 8 {
		k = unsafe.Pointer(uintptr(k) << 10)
	}
	if casp(&k, nil, nil) {
		throw("casp1")
	}
	k1 = add(k, 1)
	if !casp(&k, k, k1) {
		throw("casp2")
	}
	if k != k1 {
		throw("casp3")
	}

	m = [4]byte{1, 1, 1, 1}
	atomic.Or8(&m[1], 0xf0)
	if m[0] != 1 || m[1] != 0xf1 || m[2] != 1 || m[3] != 1 {
		throw("atomicor8")
	}

	*(*uint64)(unsafe.Pointer(&j)) = ^uint64(0)
	if j == j {
		throw("float64nan")
	}
	if !(j != j) {
		throw("float64nan1")
	}

	*(*uint64)(unsafe.Pointer(&j1)) = ^uint64(1)
	if j == j1 {
		throw("float64nan2")
	}
	if !(j != j1) {
		throw("float64nan3")
	}

	*(*uint32)(unsafe.Pointer(&i)) = ^uint32(0)
	if i == i {
		throw("float32nan")
	}
	if i == i {
		throw("float32nan1")
	}

	*(*uint32)(unsafe.Pointer(&i1)) = ^uint32(1)
	if i == i1 {
		throw("float32nan2")
	}
	if i == i1 {
		throw("float32nan3")
	}

	testAtomic64()

	// if _FixedStack != round2(_FixedStack) {
	// 	throw("FixedStack is not power-of-2")
	// }

	if !checkASM() {
		throw("assembly checks failed")
	}
}
Esempio n. 22
0
// getprofile blocks until the next block of profiling data is available
// and returns it as a []byte. It is called from the writing goroutine.
func (p *cpuProfile) getprofile() []byte {
	if p == nil {
		return nil
	}

	if p.wholding {
		// Release previous log to signal handling side.
		// Loop because we are racing against SetCPUProfileRate(0).
		for {
			n := p.handoff
			if n == 0 {
				print("runtime: phase error during cpu profile handoff\n")
				return nil
			}
			if n&0x80000000 != 0 {
				p.wtoggle = 1 - p.wtoggle
				p.wholding = false
				p.flushing = true
				goto Flush
			}
			if atomic.Cas(&p.handoff, n, 0) {
				break
			}
		}
		p.wtoggle = 1 - p.wtoggle
		p.wholding = false
	}

	if p.flushing {
		goto Flush
	}

	if !p.on && p.handoff == 0 {
		return nil
	}

	// Wait for new log.
	notetsleepg(&p.wait, -1)
	noteclear(&p.wait)

	switch n := p.handoff; {
	case n == 0:
		print("runtime: phase error during cpu profile wait\n")
		return nil
	case n == 0x80000000:
		p.flushing = true
		goto Flush
	default:
		n &^= 0x80000000

		// Return new log to caller.
		p.wholding = true

		return uintptrBytes(p.log[p.wtoggle][:n])
	}

	// In flush mode.
	// Add is no longer being called. We own the log.
	// Also, p.handoff is non-zero, so flushlog will return false.
	// Evict the hash table into the log and return it.
Flush:
	for i := range p.hash {
		b := &p.hash[i]
		for j := range b.entry {
			e := &b.entry[j]
			if e.count > 0 && !p.evict(e, p.flushlog) {
				// Filled the log. Stop the loop and return what we've got.
				break Flush
			}
		}
	}

	// Return pending log data.
	if p.nlog > 0 {
		// Note that we're using toggle now, not wtoggle,
		// because we're working on the log directly.
		n := p.nlog
		p.nlog = 0
		return uintptrBytes(p.log[p.toggle][:n])
	}

	// Made it through the table without finding anything to log.
	if !p.eodSent {
		// We may not have space to append this to the partial log buf,
		// so we always return a new slice for the end-of-data marker.
		p.eodSent = true
		return uintptrBytes(eod[:])
	}

	// Finally done. Clean up and return nil.
	p.flushing = false
	if !atomic.Cas(&p.handoff, p.handoff, 0) {
		print("runtime: profile flush racing with something\n")
	}
	return nil
}
Esempio n. 23
0
File: mstkbar.go Progetto: gmwu/go
// gcLockStackBarriers synchronizes with tracebacks of gp's stack
// during sigprof for installation or removal of stack barriers. It
// blocks until any current sigprof is done tracebacking gp's stack
// and then disallows profiling tracebacks of gp's stack.
//
// This is necessary because a sigprof during barrier installation or
// removal could observe inconsistencies between the stkbar array and
// the stack itself and crash.
//
//go:nosplit
func gcLockStackBarriers(gp *g) {
	acquirem()
	for !atomic.Cas(&gp.stackLock, 0, 1) {
		osyield()
	}
}
Esempio n. 24
0
// Allocate a span to use in an MCache.
func (c *mcentral) cacheSpan() *mspan {
	// Deduct credit for this span allocation and sweep if necessary.
	spanBytes := uintptr(class_to_allocnpages[c.sizeclass]) * _PageSize
	deductSweepCredit(spanBytes, 0)

	lock(&c.lock)
	sg := mheap_.sweepgen
retry:
	var s *mspan
	for s = c.nonempty.first; s != nil; s = s.next {
		if s.sweepgen == sg-2 && atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			c.nonempty.remove(s)
			c.empty.insertBack(s)
			unlock(&c.lock)
			s.sweep(true)
			goto havespan
		}
		if s.sweepgen == sg-1 {
			// the span is being swept by background sweeper, skip
			continue
		}
		// we have a nonempty span that does not require sweeping, allocate from it
		c.nonempty.remove(s)
		c.empty.insertBack(s)
		unlock(&c.lock)
		goto havespan
	}

	for s = c.empty.first; s != nil; s = s.next {
		if s.sweepgen == sg-2 && atomic.Cas(&s.sweepgen, sg-2, sg-1) {
			// we have an empty span that requires sweeping,
			// sweep it and see if we can free some space in it
			c.empty.remove(s)
			// swept spans are at the end of the list
			c.empty.insertBack(s)
			unlock(&c.lock)
			s.sweep(true)
			freeIndex := s.nextFreeIndex()
			if freeIndex != s.nelems {
				s.freeindex = freeIndex
				goto havespan
			}
			lock(&c.lock)
			// the span is still empty after sweep
			// it is already in the empty list, so just retry
			goto retry
		}
		if s.sweepgen == sg-1 {
			// the span is being swept by background sweeper, skip
			continue
		}
		// already swept empty span,
		// all subsequent ones must also be either swept or in process of sweeping
		break
	}
	unlock(&c.lock)

	// Replenish central list if empty.
	s = c.grow()
	if s == nil {
		return nil
	}
	lock(&c.lock)
	c.empty.insertBack(s)
	unlock(&c.lock)

	// At this point s is a non-empty span, queued at the end of the empty list,
	// c is unlocked.
havespan:
	cap := int32((s.npages << _PageShift) / s.elemsize)
	n := cap - int32(s.allocCount)
	if n == 0 || s.freeindex == s.nelems || uintptr(s.allocCount) == s.nelems {
		throw("span has no free objects")
	}
	usedBytes := uintptr(s.allocCount) * s.elemsize
	if usedBytes > 0 {
		reimburseSweepCredit(usedBytes)
	}
	atomic.Xadd64(&memstats.heap_live, int64(spanBytes)-int64(usedBytes))
	if trace.enabled {
		// heap_live changed.
		traceHeapAlloc()
	}
	if gcBlackenEnabled != 0 {
		// heap_live changed.
		gcController.revise()
	}
	s.incache = true
	freeByteBase := s.freeindex &^ (64 - 1)
	whichByte := freeByteBase / 8
	// Init alloc bits cache.
	s.refillAllocCache(whichByte)

	// Adjust the allocCache so that s.freeindex corresponds to the low bit in
	// s.allocCache.
	s.allocCache >>= s.freeindex % 64

	return s
}
Esempio n. 25
0
func createfing() {
	// start the finalizer goroutine exactly once
	if fingCreate == 0 && atomic.Cas(&fingCreate, 0, 1) {
		go runfinq()
	}
}
Esempio n. 26
0
// SetCPUProfileRate sets the CPU profiling rate to hz samples per second.
// If hz <= 0, SetCPUProfileRate turns off profiling.
// If the profiler is on, the rate cannot be changed without first turning it off.
//
// Most clients should use the runtime/pprof package or
// the testing package's -test.cpuprofile flag instead of calling
// SetCPUProfileRate directly.
func SetCPUProfileRate(hz int) {
	// Clamp hz to something reasonable.
	if hz < 0 {
		hz = 0
	}
	if hz > 1000000 {
		hz = 1000000
	}

	lock(&cpuprofLock)
	if hz > 0 {
		if cpuprof == nil {
			cpuprof = (*cpuProfile)(sysAlloc(unsafe.Sizeof(cpuProfile{}), &memstats.other_sys))
			if cpuprof == nil {
				print("runtime: cpu profiling cannot allocate memory\n")
				unlock(&cpuprofLock)
				return
			}
		}
		if cpuprof.on || cpuprof.handoff != 0 {
			print("runtime: cannot set cpu profile rate until previous profile has finished.\n")
			unlock(&cpuprofLock)
			return
		}

		cpuprof.on = true
		// pprof binary header format.
		// https://github.com/gperftools/gperftools/blob/master/src/profiledata.cc#L119
		p := &cpuprof.log[0]
		p[0] = 0                 // count for header
		p[1] = 3                 // depth for header
		p[2] = 0                 // version number
		p[3] = uintptr(1e6 / hz) // period (microseconds)
		p[4] = 0
		cpuprof.nlog = 5
		cpuprof.toggle = 0
		cpuprof.wholding = false
		cpuprof.wtoggle = 0
		cpuprof.flushing = false
		cpuprof.eodSent = false
		noteclear(&cpuprof.wait)

		setcpuprofilerate(int32(hz))
	} else if cpuprof != nil && cpuprof.on {
		setcpuprofilerate(0)
		cpuprof.on = false

		// Now add is not running anymore, and getprofile owns the entire log.
		// Set the high bit in cpuprof.handoff to tell getprofile.
		for {
			n := cpuprof.handoff
			if n&0x80000000 != 0 {
				print("runtime: setcpuprofile(off) twice\n")
			}
			if atomic.Cas(&cpuprof.handoff, n, n|0x80000000) {
				if n == 0 {
					// we did the transition from 0 -> nonzero so we wake getprofile
					notewakeup(&cpuprof.wait)
				}
				break
			}
		}
	}
	unlock(&cpuprofLock)
}