linux-kernel - [PATCH] x86: move warning message of polling idle and HT enabled

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Message-ID: <478C1475.7060706@ct.jp.nec.com>
Date:	Mon, 14 Jan 2008 18:03:33 -0800
From:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	tglx@...utronix.de, hpa@...or.com, linux-kernel@...r.kernel.org
Subject: [PATCH] x86: move warning message of polling idle and HT enabled

From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
Subject: [PATCH] x86: move warning message of polling idle and HT enabled

This warning at idle_setup() is never shown because smp_num_sibling hasn't
been updated at this point yet.

Move this polling idle and HT enabled warning message to select_idle_routine().
I also implement this warning on 64-bit kernel and make select_idle_routine()
call after detect_ht() call.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
---
Ingo, this patch needs Andi's patch;
i386: Move MWAIT idle check to generic CPU
http://lkml.org/lkml/2008/1/2/358
I haven't found it in x86.git tree.

 arch/x86/kernel/process_32.c |   18 ++++++++++++------
 arch/x86/kernel/process_64.c |   17 ++++++++++++-----
 arch/x86/kernel/setup_64.c   |    3 ++-
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 69a69c3..d52c032 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -287,17 +287,27 @@ static void mwait_idle(void)
 
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
+	static int selected;
+
+	if (selected)
+		return;
+#ifdef CONFIG_X86_SMP
+	if (pm_idle == poll_idle && smp_num_siblings > 1) {
+		printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
+			" performance may degrade.\n");
+	}
+#endif
 	if (cpu_has(c, X86_FEATURE_MWAIT)) {
-		printk("monitor/mwait feature present.\n");
 		/*
 		 * Skip, if setup has overridden idle.
 		 * One CPU supports mwait => All CPUs supports mwait
 		 */
 		if (!pm_idle) {
-			printk("using mwait in idle threads.\n");
+			printk(KERN_INFO "using mwait in idle threads.\n");
 			pm_idle = mwait_idle;
 		}
 	}
+	selected = 1;
 }
 
 static int __init idle_setup(char *str)
@@ -305,10 +315,6 @@ static int __init idle_setup(char *str)
 	if (!strcmp(str, "poll")) {
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
-#ifdef CONFIG_X86_SMP
-		if (smp_num_siblings > 1)
-			printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
-#endif
 	} else if (!strcmp(str, "mwait"))
 		force_mwait = 1;
 	else
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 5e12edd..8cff606 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -282,20 +282,27 @@ static void mwait_idle(void)
 
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
-	static int printed;
+	static int selected;
+
+	if (selected)
+		return;
+#ifdef CONFIG_X86_SMP
+	if (pm_idle == poll_idle && smp_num_siblings > 1) {
+		printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
+			" performance may degrade.\n");
+	}
+#endif
 	if (cpu_has(c, X86_FEATURE_MWAIT)) {
 		/*
 		 * Skip, if setup has overridden idle.
 		 * One CPU supports mwait => All CPUs supports mwait
 		 */
 		if (!pm_idle) {
-			if (!printed) {
-				printk(KERN_INFO "using mwait in idle threads.\n");
-				printed = 1;
-			}
+			printk(KERN_INFO "using mwait in idle threads.\n");
 			pm_idle = mwait_idle;
 		}
 	}
+	selected = 1;
 }
 
 static int __init idle_setup(char *str)
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index c8dcdd2..8ebf990 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -1067,7 +1067,6 @@ void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 		break;
 	}
 
-	select_idle_routine(c);
 	detect_ht(c);
 
 	/*
@@ -1085,6 +1084,8 @@ void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_MCE
 	mcheck_init(c);
 #endif
+	select_idle_routine(c);
+
 	if (c != &boot_cpu_data)
 		mtrr_ap_init();
 #ifdef CONFIG_NUMA
-- 
1.5.3.6


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