linux-kernel - [tip:x86/debug] x86: Limit number of per cpu TSC sync messages

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Message-ID: <tip-9b3660a55a9052518c91cc7c62d89e22f3f6f490@git.kernel.org>
Date:	Thu, 26 Nov 2009 09:55:16 GMT
From:	tip-bot for Mike Travis <travis@....com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...hat.com, rusty@...tcorp.com.au, fweisbec@...il.com,
	yhlu.kernel@...il.com, rostedt@...dmis.org, gregkh@...e.de,
	heiko.carstens@...ibm.com, tglx@...utronix.de, rientjes@...gle.com,
	linux-kernel@...r.kernel.org, hpa@...or.com, andi@...stfloor.org,
	travis@....com, seto.hidetoshi@...fujitsu.com,
	rdunlap@...otime.net, rdreier@...co.com, steiner@....com,
	tj@...nel.org, mingo@...e.hu
Subject: [tip:x86/debug] x86: Limit number of per cpu TSC sync messages

Commit-ID:  9b3660a55a9052518c91cc7c62d89e22f3f6f490
Gitweb:     http://git.kernel.org/tip/9b3660a55a9052518c91cc7c62d89e22f3f6f490
Author:     Mike Travis <travis@....com>
AuthorDate: Tue, 17 Nov 2009 18:22:16 -0600
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 26 Nov 2009 10:17:45 +0100

x86: Limit number of per cpu TSC sync messages

Limit the number of per cpu TSC sync messages by only printing
to the console if an error occurs, otherwise print as a DEBUG
message.

The info message "Skipping synchronization ..." is only printed
after the last cpu has booted.

Signed-off-by: Mike Travis <travis@....com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Roland Dreier <rdreier@...co.com>
Cc: Randy Dunlap <rdunlap@...otime.net>
Cc: Tejun Heo <tj@...nel.org>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: Greg Kroah-Hartman <gregkh@...e.de>
Cc: Yinghai Lu <yhlu.kernel@...il.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc: Jack Steiner <steiner@....com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
LKML-Reference: <20091118002222.181053000@...atraz.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/tsc_sync.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index f379309..eed1568 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -114,13 +114,12 @@ void __cpuinit check_tsc_sync_source(int cpu)
 		return;
 
 	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) {
-		printk_once(KERN_INFO "Skipping synchronization checks as TSC is reliable.\n");
+		if (cpu == (nr_cpu_ids-1) || system_state != SYSTEM_BOOTING)
+			pr_info(
+			"Skipped synchronization checks as TSC is reliable.\n");
 		return;
 	}
 
-	pr_info("checking TSC synchronization [CPU#%d -> CPU#%d]:",
-		smp_processor_id(), cpu);
-
 	/*
 	 * Reset it - in case this is a second bootup:
 	 */
@@ -142,12 +141,14 @@ void __cpuinit check_tsc_sync_source(int cpu)
 		cpu_relax();
 
 	if (nr_warps) {
-		printk("\n");
+		pr_warning("TSC synchronization [CPU#%d -> CPU#%d]:\n",
+			smp_processor_id(), cpu);
 		pr_warning("Measured %Ld cycles TSC warp between CPUs, "
 			   "turning off TSC clock.\n", max_warp);
 		mark_tsc_unstable("check_tsc_sync_source failed");
 	} else {
-		printk(" passed.\n");
+		pr_debug("TSC synchronization [CPU#%d -> CPU#%d]: passed\n",
+			smp_processor_id(), cpu);
 	}
 
 	/*
--
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