From efc12b8e616ed3394468c1802da8e1f39e387cd3 Mon Sep 17 00:00:00 2001
From: rsc <rsc>
Date: Mon, 27 Aug 2007 13:34:35 +0000
Subject: Replace yield system call with sleep.

---
 sysproc.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'sysproc.c')

diff --git a/sysproc.c b/sysproc.c
index 8cf3291..48fbe37 100644
--- a/sysproc.c
+++ b/sysproc.c
@@ -70,8 +70,21 @@ sys_sbrk(void)
 }
 
 int
-sys_yield(void)
+sys_sleep(void)
 {
-  yield();
+  int n, ticks0;
+  
+  if(argint(0, &n) < 0)
+    return -1;
+  acquire(&tickslock);
+  ticks0 = ticks;
+  while(ticks - ticks0 < n){
+    if(cp->killed){
+      release(&tickslock);
+      return -1;
+    }
+    sleep(&ticks, &tickslock);
+  }
+  release(&tickslock);
   return 0;
 }
-- 
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