From f4708cee467b0782e1c368734c62ff032aa24f6a Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 1 Sep 1998 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1998-09-01

---
 ip/tcp.c       |  2 +-
 port/proc.c    | 59 ++++++++++++++++++++++++++------------------------
 port/sysfile.c |  4 +++-
 3 files changed, 35 insertions(+), 30 deletions(-)

diff --git a/ip/tcp.c b/ip/tcp.c
index 11444f04181397ee9e635324ab2413efb75e69b1..03ef95e88139bd6d1826ee9d137ab3d67d85f5f2 100644
--- a/ip/tcp.c
+++ b/ip/tcp.c
@@ -1509,7 +1509,7 @@ tcpoutput(Conv *s)
 		sent = tcb->snd.ptr - tcb->snd.una;
 
 		/* Don't send anything else until our SYN has been acked */
-		if(sent != 0 && (tcb->flags & (SYNACK|FORCE)) == 0)
+		if(tcb->snd.ptr != tcb->iss && (tcb->flags & SYNACK) == 0)
 			break;
 
 		/* Compute usable segment based on offered window and limit
diff --git a/port/proc.c b/port/proc.c
index d9f8157bf918753edd06123ff56fca9109b153fe..033e7d36f42126f8e3c7923aebac8d336765ee89 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -186,9 +186,9 @@ ready(Proc *p)
 Proc*
 runproc(void)
 {
-	int i;
-	Schedq *rq;
+	Schedq *rq, *xrq;
 	Proc *p, *l;
+	ulong rt;
 
 loop:
 
@@ -198,41 +198,44 @@ loop:
 	 */
 	spllo();
 	for(;;){
-		/*
-		 *  get lowest priority process that this
-		 *  processor can run given affinity constraints
-		 *  and that hasn't run in a while
-		 */
-		if((m->fairness++ & 3) == 0){
+		if((++(m->fairness) & 3) == 0){
+			/*
+			 *  once in a while, run process that's been waiting longest
+			 *  regardless of movetime
+			 */
+			rt = 0xffffffff;
+			xrq = nil;
 			for(rq = runq; rq < &runq[Nrq]; rq++){
+				p = rq->head;
+				if(p == 0)
+					continue;
+				if(p->readytime < rt){
+					xrq = rq;
+					rt = p->readytime;
+				}
+			}
+			if(xrq != nil){
+				rq = xrq;
+				p = rq->head;
+				if(p != nil)
+					p->movetime = 0;
+			}
+		} else {
+			/*
+			 *  get highest priority process that this
+			 *  processor can run given affinity constraints
+			 */
+			for(rq = &runq[Nrq-1]; rq >= runq; rq--){
 				p = rq->head;
 				if(p == 0)
 					continue;
 				for(; p; p = p->rnext){
-					if(p->mp != MACHP(m->machno))
-					if(p->movetime >= m->ticks)
-						continue;
-					i = m->ticks - p->readytime;
-					if(i >= 2*nrdy*p->art)
+					if(p->mp == MACHP(m->machno)
+					|| p->movetime < m->ticks)
 						goto found;
 				}
 			}
 		}
-
-		/*
-		 *  get highest priority process that this
-		 *  processor can run given affinity constraints
-		 */
-		for(rq = &runq[Nrq-1]; rq >= runq; rq--){
-			p = rq->head;
-			if(p == 0)
-				continue;
-			for(; p; p = p->rnext){
-				if(p->mp == MACHP(m->machno)
-				|| p->movetime < m->ticks)
-					goto found;
-			}
-		}
 	}
 
 found:
diff --git a/port/sysfile.c b/port/sysfile.c
index a039e164c318efd211923f439d97095947eaea06..488e6163ec4beeb8e63a1de1e5b29f79cc42daf3 100644
--- a/port/sysfile.c
+++ b/port/sysfile.c
@@ -291,11 +291,13 @@ unionread(Chan *c, void *va, long n)
 	for(i = 0; mount != nil && i < c->uri; i++)
 		mount = mount->next;
 
-	for(;;) {
+	while(mount != nil) {
 		if(waserror()) {
 			runlock(&m->lock);
 			nexterror();
 		}
+		if(mount->to == nil)
+			goto next;
 		nc = cclone(mount->to, 0);
 		poperror();