linux-kernel - [PATCH 1/2] x86: Reduce verbosity of "TSC is reliable" message

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Message-ID: <adazl8l2swc.fsf@cisco.com>
Date:	Wed, 23 Sep 2009 15:33:23 -0700
From:	Roland Dreier <rdreier@...co.com>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] 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>
---
 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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