From fcacce0f2f510b21930052fcc0e07103db33a5b3 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@gmx.de>
Date: Tue, 16 Oct 2012 16:10:26 +0200
Subject: kernel: duppage cleanup

remove the sched() call and retry loop from duppage() and just
drop the page lock, then reacquire it after lock(&palloc).
---
 sys/src/9/port/page.c | 30 ++++++++----------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

(limited to 'sys/src/9/port/page.c')

diff --git a/sys/src/9/port/page.c b/sys/src/9/port/page.c
index b004152e9..e8c5b6ce0 100644
--- a/sys/src/9/port/page.c
+++ b/sys/src/9/port/page.c
@@ -264,29 +264,11 @@ auxpage(void)
 	return p;
 }
 
-static int dupretries = 15000;
-
 void
 duppage(Page *p)				/* Always call with p locked */
 {
 	Page *np;
 	int color;
-	int retries;
-
-	retries = 0;
-retry:
-	/* don't dup pages that are shared or have no image */
-	if(p->ref != 1 || p->image == nil || p->image->notext)
-		return;
-
-	if(retries++ > dupretries){
-		print("duppage %d, up %p\n", retries, up);
-		dupretries += 100;
-		if(dupretries > 100000)
-			panic("duppage");
-		uncachepage(p);
-		return;
-	}
 
 	/*
 	 *  normal lock ordering is to call
@@ -295,14 +277,18 @@ retry:
 	 *  our locks and try again. as the page
 	 *  is from the image cache, this might
 	 *  let someone else come in and grab it
-	 *  so we check page ref above.
+	 *  so we check page ref below.
 	 */
 	if(!canlock(&palloc)){
 		unlock(p);
-		if(up)
-			sched();
+		lock(&palloc);
 		lock(p);
-		goto retry;
+	}
+
+	/* don't dup pages that are shared or have no image */
+	if(p->ref != 1 || p->image == nil || p->image->notext){
+		unlock(&palloc);
+		return;
 	}
 
 	/* No freelist cache when memory is very low */
-- 
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