From f5d804c9da2b89ed0e4169bc76d3643ba1dee8eb Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Fri, 6 Jan 1995 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1995-01-06

---
 pc/devastar.c  |  6 +++---
 port/auth.c    |  4 +++-
 port/devpipe.c |  2 ++
 port/devproc.c |  4 +---
 port/portdat.h |  3 ++-
 port/proc.c    | 32 +++++++++++++++-----------------
 port/sysproc.c | 14 ++++++++++----
 7 files changed, 36 insertions(+), 29 deletions(-)

diff --git a/pc/devastar.c b/pc/devastar.c
index c278bf7cd30d41d67d00bbc796915b83ee41d6a6..03c2a80102a26518242f02d0a665a5e0dd908181 100644
--- a/pc/devastar.c
+++ b/pc/devastar.c
@@ -411,14 +411,14 @@ astarreset(void)
 		}
 
 		/* defaults */
-		if(a->mem == 0)
-			a->mem = 0xD4000;
 		if(a->irq == 0)
 			a->irq = 15;
 		a->id = i;
 
-		if(getisa(a->mem, Pagesize, 0) == 0)
+		a->mem = getisa(a->mem, Pagesize, Pagesize);
+		if(a->mem == 0)
 			panic("astarreset: %lux", a->mem);
+		a->mem & ~KZERO;
 
 		if(astarsetup(a) < 0){
 			xfree(a);
diff --git a/port/auth.c b/port/auth.c
index b694cd8e35dd87294017de92401dc7d3f1a9ecd9..2c2e3b4730fb3d250b2bcbd080f1628d862349d7 100644
--- a/port/auth.c
+++ b/port/auth.c
@@ -124,8 +124,10 @@ sysfsession(ulong *arg)
 	unlock(c);
 
 	/* back off if someone else is doing an fsession */
-	while(!canlock(&s->send))
+	while(!canlock(&s->send)) {
+		up->yield = 1;
 		sched();
+	}
 
 	if(s->valid == 0){
 		/*
diff --git a/port/devpipe.c b/port/devpipe.c
index cef15394661feb1adcaf17022c34138d795ab650..d1857a54e3e9147dce21270e8ad9195e012324de 100644
--- a/port/devpipe.c
+++ b/port/devpipe.c
@@ -302,6 +302,8 @@ pipewrite(Chan *c, void *va, long n, ulong offset)
 
 	USED(offset);
 
+	if((getstatus()&IE) == 0)
+		print("pipewrite hi %lux\n", getcallerpc(c));
 	if(waserror()) {
 		/* avoid notes when pipe is a mounted queue */
 		if((c->flag & CMSG) == 0)
diff --git a/port/devproc.c b/port/devproc.c
index 79a74c9d72659d164447666be83dde925ef4f1c2..9813bd97a22f43be4f41429c7bae1ceae6962959 100644
--- a/port/devproc.c
+++ b/port/devproc.c
@@ -815,10 +815,8 @@ procctlmemio(Proc *p, ulong offset, int n, void *va, int read)
 	b += offset&(BY2PG-1);
 	if(read == 1)
 		memmove(a, b, n);
-	else {
+	else
 		memmove(b, a, n);
-		dcflush(b, n);
-	}
 	kunmap(k);
 
 	/* Ensure the process sees text page changes */
diff --git a/port/portdat.h b/port/portdat.h
index 13a0297394c127dbe34cb154179f7f596f1caf6d..e33273e3d4270b863cdf7923699c910ab35544f0 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -586,7 +586,8 @@ struct Proc
 
 	Mach	*wired;		/* machine this process must run on */
 	int	pri;		/* scheduling priority - low is high priority */
-	int	nice;		/* time-passing algorithm - low is high priority */
+	short	nice;		/* time-passing algorithm - low is high priority */
+	short	yield;		/* force one lap in the runq */	
 
 	void	*ureg;		/* User registers for notes */
 	void	*dbgreg;	/* User registers for devproc */
diff --git a/port/proc.c b/port/proc.c
index 8527082377ea55425a85bec5f9154c29490c7fc5..e1fb2a12aa3098ce91299d0b5589e85d705fe376 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -119,7 +119,7 @@ anyhigher(void)
 	for(p=runq.head; p; p=p->rnext)
 		if(p->pri < pri)
 			if(p->wired == 0 || p->wired == m)
-				return runq.n;
+				return 1;
 	return 0;
 }
 
@@ -152,18 +152,12 @@ loop:
 	spllo();
 
 	/* look for potential proc while not locked */
-	for(p=runq.head; p; p=p->rnext) {
+	for(p = runq.head; p; p=p->rnext) {
 		/*
-		 *  state is not saved
+		 *  state is not saved or wired to another machine
 		 */
-		if(p->mach)
-			continue;
-		/*
-		 *  wired to another machine
-		 */
-		if(p->wired && p->wired != m)
-			continue;
-		break;
+		if(!(p->mach || (p->wired && p->wired != m)))
+			break;
 	}
 	if(p == 0)
 		goto loop;
@@ -173,12 +167,14 @@ loop:
 
 	/* find best proc while locked */
 	bp = 0;
-	for(p=runq.head; p; p=p->rnext) {
-		if(p->mach)
-			continue;
-		if(p->wired && p->wired != m)
+	for(p = runq.head; p; p=p->rnext) {
+		if(p->mach || (p->wired && p->wired != m))
 			continue;
-		if(bp == 0 || p->pri < bp->pri)
+		if(bp == 0) {
+			p->yield = 0;
+			bp = p;
+		} else
+		if(p->yield == 0 && p->pri < bp->pri)
 			bp = p;
 	}
 	if(bp == 0) {
@@ -368,8 +364,10 @@ sleep(Rendez *r, int (*f)(void*), void *arg)
 	int s;
 
 	sleep1(r, f, arg);
-	if(up->notepending == 0)
+	if(up->notepending == 0) {
+		up->yield = 1;
 		sched();	/* notepending may go true while asleep */
+	}
 
 	if(up->notepending) {
 		up->notepending = 0;
diff --git a/port/sysproc.c b/port/sysproc.c
index 51ba8dfb7b28ba8e0bf3960271088ccb3131b7a5..d27cd7bcd69adfe18bdbead01a3e96ef0d5de5fa 100644
--- a/port/sysproc.c
+++ b/port/sysproc.c
@@ -462,11 +462,17 @@ return0(void *a)
 long
 syssleep(ulong *arg)
 {
-	if(arg[0] == 0)
-		sched();
-	else
-		tsleep(&up->sleep, return0, 0, arg[0]);
+	int n;
 
+	n = arg[0];
+	if(n == 0) {
+		up->yield = 1;
+		sched();
+		return 0;
+	} 
+	if(MS2TK(n) == 0)
+		n = TK2MS(1);
+	tsleep(&up->sleep, return0, 0, n);
 	return 0;
 }