linux-kernel - [tip:x86/urgent] x86: Reduce verbosity of "TSC is reliable" message

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Message-ID: <tip-ea01c0d7315d6e3218fd22a6947c5b09305fcf65@git.kernel.org>
Date:	Thu, 24 Sep 2009 09:37:29 GMT
From:	tip-bot for Roland Dreier <rdreier@...co.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	rdreier@...co.com, rolandd@...co.com, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:x86/urgent] x86: Reduce verbosity of "TSC is reliable" message

Commit-ID:  ea01c0d7315d6e3218fd22a6947c5b09305fcf65
Gitweb:     http://git.kernel.org/tip/ea01c0d7315d6e3218fd22a6947c5b09305fcf65
Author:     Roland Dreier <rdreier@...co.com>
AuthorDate: Wed, 23 Sep 2009 15:33:23 -0700
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 24 Sep 2009 11:35:19 +0200

x86: Reduce verbosity of "TSC is reliable" message

On modern systems, the kernel prints the message

    Skipping synchronization checks as TSC is reliable.

once for every non-boot CPU.

This gets kind of ridiculous on huge systems; for example, on a
64-thread system I was lucky enough to get:

    $ dmesg | grep 'TSC is reliable' | wc
         63     567    4221

There's no point to doing this for every CPU, since the code is
just checking the boot CPU anyway, so change this to a
printk_once() to make the message appears only once.

Signed-off-by: Roland Dreier <rolandd@...co.com>
LKML-Reference: <adazl8l2swc.fsf@...co.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 arch/x86/kernel/tsc_sync.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 027b5b4..f379309 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -114,7 +114,7 @@ void __cpuinit check_tsc_sync_source(int cpu)
 		return;
 
 	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) {
-		pr_info("Skipping synchronization checks as TSC is reliable.\n");
+		printk_once(KERN_INFO "Skipping synchronization checks as TSC is reliable.\n");
 		return;
 	}
 
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