code: 9ferno

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inferno fine tuning to 9front taslock.c

--- a/os/port/taslock.c

+++ b/os/port/taslock.c

@@ -50,6 +50,7 @@

 		dumpaproc(p);

 }

+/* if looped to obtain a lock, return 1. Else, return 0 */

 int

 lock(Lock *l)

 {

@@ -61,7 +62,7 @@

 	lockstats.locks++;

 	if(up)

 		up->nlocks++;	/* prevent being scheded */

-	if(tas(&l->key) == 0){

+	if(tas(&l->key) == 0){ /* got the lock on the 1st attempt, done */

 		if(up)

 			up->lastlock = l;

 		l->pc = pc;

@@ -81,14 +82,17 @@

 		lockstats.inglare++;

 		i = 0;

 		while(l->key){

-			if(conf.nmach < 2 && up && up->edf && (up->edf->flags & Admitted)){

+			if(conf.nmach < 2 && up && up->state == Running && islo()

+				/* && up->edf && (up->edf->flags & Admitted)*/){

 				/*

 				 * Priority inversion, yield on a uniprocessor; on a

 				 * multiprocessor, the other processor will unlock

 				 */

-				print("inversion %#p pc %#p proc %lud held by pc %#p proc %lud\n",

+				print("inversion %#p pc %#p proc %zud held by pc %#p proc %zud\n",

 					l, pc, up != nil ? up->pid : 0, l->pc, l->p != nil ? ((Proc*)l->p)->pid : 0);

-				up->edf->d = todget(nil);	/* yield to process with lock */

+				/* up->edf->d = todget(nil);*/	/* yield to process with lock */

+				up->pc = pc;

+				sched();

 			}

 			if(i++ > 100000000){

 				i = 0;

@@ -98,8 +102,11 @@

 		if(up)

 			up->nlocks++;

 		if(tas(&l->key) == 0){

-			if(up)

+			if(up){

 				up->lastlock = l;

+				l->priority = up->priority;

+				up->priority = PriLock;

+			}

 			l->pc = pc;

 			l->p = up;

 			l->m = MACHP(m->machno);

@@ -126,6 +133,10 @@

 	x = splhi();

 	if(tas(&l->key) != 0){

 		lockstats.glare++;

+		if(conf.nmach < 2)

+			panic("ilock: no way out: pc 0x%zux:"

+					" lock 0x%p held by pc 0x%zux",

+					pc, l, l->pc);

 		/*

 		 * Cannot also check l->pc, l->m, or l->isilock here

 		 * because they might just not be set yet, or

@@ -160,14 +171,17 @@

 {

 	if(up)

 		up->nlocks++;

-	if(tas(&l->key)){

+	if(tas(&l->key) != 0){

 		if(up)

 			up->nlocks--;

 		return 0;

 	}

-	if(up)

+	if(up){

 		up->lastlock = l;

+		l->priority = up->priority;

+		up->priority = PriLock;

+	}

 	l->pc = getcallerpc(&l);

 	l->p = up;

 	l->m = MACHP(m->machno);

@@ -181,6 +195,7 @@

 void

 unlock(Lock *l)

 {

+	int pri;

 #ifdef LOCKCYCLES

 	l->lockcycles += lcycles();

 	cumlockcycles += l->lockcycles;

@@ -201,16 +216,22 @@

 		dumpaproc(l->p);

 		dumpaproc(up);

 	}

-	l->m = nil;

+	pri = l->priority;

+	l->m = l->p = nil;

+	l->pc = 0;

 	coherence();

 	l->key = 0;

-	if(up && --up->nlocks == 0 && up->delaysched && islo()){

-		/*

-		 * Call sched if the need arose while locks were held

-		 * But, don't do it from interrupt routines, hence the islo() test

-		 */

-		sched();

+	if(up){

+		up->priority = pri;

+		up->lastlock = nil;

+		if(--up->nlocks == 0 && up->delaysched && islo()){

+			/*

+			 * Call sched if the need arose while locks were held

+			 * But, don't do it from interrupt routines, hence the islo() test

+			 */

+			sched();

+		}

 	}

 }

@@ -240,7 +261,8 @@

 		print("iunlock(%#p) while lo: pc %#p, held by %#p\n", l, getcallerpc(&l), l->pc);

 	sr = l->sr;

-	l->m = nil;

+	l->m = l->p = nil;

+	l->sr = l->pc = 0;

 	coherence();

 	l->key = 0;

 	m->ilockdepth--;