예제 #1
0
// Put on `g' queue.  Sched must be locked.
static void
gput(G *g)
{
	M *m;

	// If g is wired, hand it off directly.
	if((m = g->lockedm) != nil && canaddmcpu()) {
		mnextg(m, g);
		return;
	}

	// If g is the idle goroutine for an m, hand it off.
	if(g->idlem != nil) {
		if(g->idlem->idleg != nil) {
			runtime·printf("m%d idle out of sync: g%d g%d\n",
				g->idlem->id,
				g->idlem->idleg->goid, g->goid);
			runtime·throw("runtime: double idle");
		}
		g->idlem->idleg = g;
		return;
	}

	g->schedlink = nil;
	if(runtime·sched.ghead == nil)
		runtime·sched.ghead = g;
	else
		runtime·sched.gtail->schedlink = g;
	runtime·sched.gtail = g;

	// increment gwait.
	// if it transitions to nonzero, set atomic gwaiting bit.
	if(runtime·sched.gwait++ == 0)
		runtime·xadd(&runtime·sched.atomic, 1<<gwaitingShift);
}
예제 #2
0
파일: proc.c 프로젝트: machinaut/go
// Put on `g' queue.  Sched must be locked.
static void
gput(G *g)
{
	M *m;

	// If g is wired, hand it off directly.
	if(runtime·sched.mcpu < runtime·sched.mcpumax && (m = g->lockedm) != nil) {
		mnextg(m, g);
		return;
	}
	
	// If g is the idle goroutine for an m, hand it off.
	if(g->idlem != nil) {
		if(g->idlem->idleg != nil) {
			runtime·printf("m%d idle out of sync: g%d g%d\n",
				g->idlem->id,
				g->idlem->idleg->goid, g->goid);
			runtime·throw("runtime: double idle");
		}
		g->idlem->idleg = g;
		return;
	}

	g->schedlink = nil;
	if(runtime·sched.ghead == nil)
		runtime·sched.ghead = g;
	else
		runtime·sched.gtail->schedlink = g;
	runtime·sched.gtail = g;
	runtime·sched.gwait++;
}
예제 #3
0
파일: proc.c 프로젝트: machinaut/go
// Get the next goroutine that m should run.
// Sched must be locked on entry, is unlocked on exit.
// Makes sure that at most $GOMAXPROCS gs are
// running on cpus (not in system calls) at any given time.
static G*
nextgandunlock(void)
{
	G *gp;

	if(runtime·sched.mcpu < 0)
		runtime·throw("negative runtime·sched.mcpu");

	// If there is a g waiting as m->nextg,
	// mnextg took care of the runtime·sched.mcpu++.
	if(m->nextg != nil) {
		gp = m->nextg;
		m->nextg = nil;
		schedunlock();
		return gp;
	}

	if(m->lockedg != nil) {
		// We can only run one g, and it's not available.
		// Make sure some other cpu is running to handle
		// the ordinary run queue.
		if(runtime·sched.gwait != 0)
			matchmg();
	} else {
		// Look for work on global queue.
		while(runtime·sched.mcpu < runtime·sched.mcpumax && (gp=gget()) != nil) {
			if(gp->lockedm) {
				mnextg(gp->lockedm, gp);
				continue;
			}
			runtime·sched.mcpu++;		// this m will run gp
			schedunlock();
			return gp;
		}
		// Otherwise, wait on global m queue.
		mput(m);
	}
	if(runtime·sched.mcpu == 0 && runtime·sched.msyscall == 0)
		runtime·throw("all goroutines are asleep - deadlock!");
	m->nextg = nil;
	m->waitnextg = 1;
	runtime·noteclear(&m->havenextg);
	if(runtime·sched.waitstop && runtime·sched.mcpu <= runtime·sched.mcpumax) {
		runtime·sched.waitstop = 0;
		runtime·notewakeup(&runtime·sched.stopped);
	}
	schedunlock();

	runtime·notesleep(&m->havenextg);
	if((gp = m->nextg) == nil)
		runtime·throw("bad m->nextg in nextgoroutine");
	m->nextg = nil;
	return gp;
}
예제 #4
0
파일: proc.c 프로젝트: machinaut/go
// Kick off new ms as needed (up to mcpumax).
// There are already `other' other cpus that will
// start looking for goroutines shortly.
// Sched is locked.
static void
matchmg(void)
{
	G *g;

	if(m->mallocing || m->gcing)
		return;
	while(runtime·sched.mcpu < runtime·sched.mcpumax && (g = gget()) != nil){
		M *m;

		// Find the m that will run g.
		if((m = mget(g)) == nil){
			m = runtime·malloc(sizeof(M));
			// Add to runtime·allm so garbage collector doesn't free m
			// when it is just in a register or thread-local storage.
			m->alllink = runtime·allm;
			runtime·allm = m;
			m->id = runtime·sched.mcount++;

			if(runtime·iscgo) {
				CgoThreadStart ts;

				if(libcgo_thread_start == nil)
					runtime·throw("libcgo_thread_start missing");
				// pthread_create will make us a stack.
				m->g0 = runtime·malg(-1);
				ts.m = m;
				ts.g = m->g0;
				ts.fn = runtime·mstart;
				runtime·asmcgocall(libcgo_thread_start, &ts);
			} else {
				if(Windows)
					// windows will layout sched stack on os stack
					m->g0 = runtime·malg(-1);
				else
					m->g0 = runtime·malg(8192);
				runtime·newosproc(m, m->g0, m->g0->stackbase, runtime·mstart);
			}
		}
		mnextg(m, g);
	}
}
예제 #5
0
// Kick off new m's as needed (up to mcpumax).
// Sched is locked.
static void
matchmg(void)
{
	G *gp;
	M *mp;

	if(m->mallocing || m->gcing)
		return;

	while(haveg() && canaddmcpu()) {
		gp = gget();
		if(gp == nil)
			runtime·throw("gget inconsistency");

		// Find the m that will run gp.
		if((mp = mget(gp)) == nil)
			mp = runtime·newm();
		mnextg(mp, gp);
	}
}
예제 #6
0
// Get the next goroutine that m should run.
// Sched must be locked on entry, is unlocked on exit.
// Makes sure that at most $GOMAXPROCS g's are
// running on cpus (not in system calls) at any given time.
static G*
nextgandunlock(void)
{
	G *gp;
	uint32 v;

top:
	if(atomic_mcpu(runtime·sched.atomic) >= maxgomaxprocs)
		runtime·throw("negative mcpu");

	// If there is a g waiting as m->nextg, the mcpu++
	// happened before it was passed to mnextg.
	if(m->nextg != nil) {
		gp = m->nextg;
		m->nextg = nil;
		schedunlock();
		return gp;
	}

	if(m->lockedg != nil) {
		// We can only run one g, and it's not available.
		// Make sure some other cpu is running to handle
		// the ordinary run queue.
		if(runtime·sched.gwait != 0) {
			matchmg();
			// m->lockedg might have been on the queue.
			if(m->nextg != nil) {
				gp = m->nextg;
				m->nextg = nil;
				schedunlock();
				return gp;
			}
		}
	} else {
		// Look for work on global queue.
		while(haveg() && canaddmcpu()) {
			gp = gget();
			if(gp == nil)
				runtime·throw("gget inconsistency");

			if(gp->lockedm) {
				mnextg(gp->lockedm, gp);
				continue;
			}
			runtime·sched.grunning++;
			schedunlock();
			return gp;
		}

		// The while loop ended either because the g queue is empty
		// or because we have maxed out our m procs running go
		// code (mcpu >= mcpumax).  We need to check that
		// concurrent actions by entersyscall/exitsyscall cannot
		// invalidate the decision to end the loop.
		//
		// We hold the sched lock, so no one else is manipulating the
		// g queue or changing mcpumax.  Entersyscall can decrement
		// mcpu, but if does so when there is something on the g queue,
		// the gwait bit will be set, so entersyscall will take the slow path
		// and use the sched lock.  So it cannot invalidate our decision.
		//
		// Wait on global m queue.
		mput(m);
	}

	// Look for deadlock situation.
	// There is a race with the scavenger that causes false negatives:
	// if the scavenger is just starting, then we have
	//	scvg != nil && grunning == 0 && gwait == 0
	// and we do not detect a deadlock.  It is possible that we should
	// add that case to the if statement here, but it is too close to Go 1
	// to make such a subtle change.  Instead, we work around the
	// false negative in trivial programs by calling runtime.gosched
	// from the main goroutine just before main.main.
	// See runtime·main above.
	//
	// On a related note, it is also possible that the scvg == nil case is
	// wrong and should include gwait, but that does not happen in
	// standard Go programs, which all start the scavenger.
	//
	if((scvg == nil && runtime·sched.grunning == 0) ||
	   (scvg != nil && runtime·sched.grunning == 1 && runtime·sched.gwait == 0 &&
	    (scvg->status == Grunning || scvg->status == Gsyscall))) {
		runtime·throw("all goroutines are asleep - deadlock!");
	}

	m->nextg = nil;
	m->waitnextg = 1;
	runtime·noteclear(&m->havenextg);

	// Stoptheworld is waiting for all but its cpu to go to stop.
	// Entersyscall might have decremented mcpu too, but if so
	// it will see the waitstop and take the slow path.
	// Exitsyscall never increments mcpu beyond mcpumax.
	v = runtime·atomicload(&runtime·sched.atomic);
	if(atomic_waitstop(v) && atomic_mcpu(v) <= atomic_mcpumax(v)) {
		// set waitstop = 0 (known to be 1)
		runtime·xadd(&runtime·sched.atomic, -1<<waitstopShift);
		runtime·notewakeup(&runtime·sched.stopped);
	}
	schedunlock();

	runtime·notesleep(&m->havenextg);
	if(m->helpgc) {
		runtime·gchelper();
		m->helpgc = 0;
		runtime·lock(&runtime·sched);
		goto top;
	}
	if((gp = m->nextg) == nil)
		runtime·throw("bad m->nextg in nextgoroutine");
	m->nextg = nil;
	return gp;
}
예제 #7
0
파일: proc.c 프로젝트: Sunmonds/gcc
// Get the next goroutine that m should run.
// Sched must be locked on entry, is unlocked on exit.
// Makes sure that at most $GOMAXPROCS g's are
// running on cpus (not in system calls) at any given time.
static G*
nextgandunlock(void)
{
	G *gp;
	uint32 v;

top:
	if(atomic_mcpu(runtime_sched.atomic) >= maxgomaxprocs)
		runtime_throw("negative mcpu");

	// If there is a g waiting as m->nextg, the mcpu++
	// happened before it was passed to mnextg.
	if(m->nextg != nil) {
		gp = m->nextg;
		m->nextg = nil;
		schedunlock();
		return gp;
	}

	if(m->lockedg != nil) {
		// We can only run one g, and it's not available.
		// Make sure some other cpu is running to handle
		// the ordinary run queue.
		if(runtime_sched.gwait != 0) {
			matchmg();
			// m->lockedg might have been on the queue.
			if(m->nextg != nil) {
				gp = m->nextg;
				m->nextg = nil;
				schedunlock();
				return gp;
			}
		}
	} else {
		// Look for work on global queue.
		while(haveg() && canaddmcpu()) {
			gp = gget();
			if(gp == nil)
				runtime_throw("gget inconsistency");

			if(gp->lockedm) {
				mnextg(gp->lockedm, gp);
				continue;
			}
			runtime_sched.grunning++;
			schedunlock();
			return gp;
		}

		// The while loop ended either because the g queue is empty
		// or because we have maxed out our m procs running go
		// code (mcpu >= mcpumax).  We need to check that
		// concurrent actions by entersyscall/exitsyscall cannot
		// invalidate the decision to end the loop.
		//
		// We hold the sched lock, so no one else is manipulating the
		// g queue or changing mcpumax.  Entersyscall can decrement
		// mcpu, but if does so when there is something on the g queue,
		// the gwait bit will be set, so entersyscall will take the slow path
		// and use the sched lock.  So it cannot invalidate our decision.
		//
		// Wait on global m queue.
		mput(m);
	}

	v = runtime_atomicload(&runtime_sched.atomic);
	if(runtime_sched.grunning == 0)
		runtime_throw("all goroutines are asleep - deadlock!");
	m->nextg = nil;
	m->waitnextg = 1;
	runtime_noteclear(&m->havenextg);

	// Stoptheworld is waiting for all but its cpu to go to stop.
	// Entersyscall might have decremented mcpu too, but if so
	// it will see the waitstop and take the slow path.
	// Exitsyscall never increments mcpu beyond mcpumax.
	if(atomic_waitstop(v) && atomic_mcpu(v) <= atomic_mcpumax(v)) {
		// set waitstop = 0 (known to be 1)
		runtime_xadd(&runtime_sched.atomic, -1<<waitstopShift);
		runtime_notewakeup(&runtime_sched.stopped);
	}
	schedunlock();

	runtime_notesleep(&m->havenextg);
	if(m->helpgc) {
		runtime_gchelper();
		m->helpgc = 0;
		runtime_lock(&runtime_sched);
		goto top;
	}
	if((gp = m->nextg) == nil)
		runtime_throw("bad m->nextg in nextgoroutine");
	m->nextg = nil;
	return gp;
}