From c7c4310f7fc1485925d800628bf50b3aeab535ef Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Mon, 10 Jul 2000 23:18:26 +0000
Subject: Merge with Linux 2.4.0-test3-pre8.  Linus has accepted most of what
 I've sent him, so we're very close to full integration of the MIPS port into
 his sources.

---
 arch/i386/kernel/entry.S   |  4 ++--
 arch/i386/kernel/process.c | 40 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 3 deletions(-)

(limited to 'arch/i386')

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index a80d61ebc..660a9e1fb 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -77,8 +77,8 @@ sigpending	=  8
 addr_limit	= 12
 exec_domain	= 16
 need_resched	= 20
-processor	= 56
-tsk_ptrace	= 60
+processor	= 48
+tsk_ptrace	= 56
 
 ENOSYS = 38
 
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index bddac2a1d..e240cc79a 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -87,13 +87,39 @@ static void default_idle(void)
 	}
 }
 
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle (void)
+{
+	int oldval;
+
+	__sti();
+
+	/*
+	 * Deal with another CPU just having chosen a thread to
+	 * run here:
+	 */
+	oldval = xchg(&current->need_resched, -1);
+
+	if (!oldval)
+		asm volatile(
+			"2:"
+			"cmpl $-1, %0;"
+			"rep; nop;"
+			"je 2b;"
+				: :"m" (current->need_resched));
+}
+
 /*
  * The idle thread. There's no useful work to be
  * done, so just try to conserve power and have a
  * low exit latency (ie sit in a loop waiting for
  * somebody to say that they'd like to reschedule)
  */
-void cpu_idle(void)
+void cpu_idle (void)
 {
 	/* endless idle loop with no priority at all */
 	init_idle();
@@ -111,6 +137,18 @@ void cpu_idle(void)
 	}
 }
 
+static int __init idle_setup (char *str)
+{
+	if (!strncmp(str, "poll", 4)) {
+		printk("using polling idle threads.\n");
+		pm_idle = poll_idle;
+	}
+
+	return 1;
+}
+
+__setup("idle=", idle_setup);
+
 static long no_idt[2] = {0, 0};
 static int reboot_mode = 0;
 static int reboot_thru_bios = 0;
-- 
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