linux-kernel - [PATCH] watchdog: reduce "NMI watchdog enabled, takes one hw-pmu counter." messages

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Date:	Wed, 6 Jun 2012 13:09:46 -0500
From:	Nathan Zimmer <nzimmer@....com>
To:	linux-kernel@...r.kernel.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Don Zickus <dzickus@...hat.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH] watchdog: reduce "NMI watchdog enabled, takes one hw-pmu
	counter." messages

 watchdog: reduces some noise on a large system
 The printk buffer can be flooded with with redundant
 "NMI watchdog enabled, takes one hw-pmu counter." messages.
 It doesn't add any value beyond the first.

 Note the message needs logged a second time if the watchdog was disabled then
 reenabled.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Don Zickus <dzickus@...hat.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Signed-off-by: Nathan Zimmer <nzimmer@....com>
---
 kernel/watchdog.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index e5e1d85..404b141 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -372,6 +372,8 @@ static int watchdog(void *unused)
 
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
+static bool already_notified;
+
 static int watchdog_nmi_enable(int cpu)
 {
 	struct perf_event_attr *wd_attr;
@@ -391,7 +393,10 @@ static int watchdog_nmi_enable(int cpu)
 	/* Try to register using hardware perf events */
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
 	if (!IS_ERR(event)) {
-		pr_info("enabled, takes one hw-pmu counter.\n");
+		if (!already_notified) {
+			pr_info("enabled, takes one hw-pmu counter.\n");
+			already_notified = true;
+		}
 		goto out_save;
 	}
 
@@ -426,6 +431,7 @@ static void watchdog_nmi_disable(int cpu)
 
 		/* should be in cleanup, but blocks oprofile */
 		perf_event_release_kernel(event);
+		already_notified = false;
 	}
 	return;
 }
-- 
1.6.0.2

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