linux-kernel - [tip:perf/urgent] perf/core: Change log level for duration warning to KERN

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Message-ID: <tip-0d87d7ec22a0879d3926faa4f4f4412a5dee1fba@git.kernel.org>
Date:	Tue, 2 Aug 2016 01:28:09 -0700
From:	tip-bot for David Ahern <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...hat.com, hpa@...or.com, jolsa@...hat.com,
	peterz@...radead.org, linux-kernel@...r.kernel.org,
	mingo@...nel.org, tglx@...utronix.de, dsa@...ulusnetworks.com,
	torvalds@...ux-foundation.org, alexander.shishkin@...ux.intel.com
Subject: [tip:perf/urgent] perf/core: Change log level for duration warning
 to KERN_INFO

Commit-ID:  0d87d7ec22a0879d3926faa4f4f4412a5dee1fba
Gitweb:     http://git.kernel.org/tip/0d87d7ec22a0879d3926faa4f4f4412a5dee1fba
Author:     David Ahern <dsa@...ulusnetworks.com>
AuthorDate: Mon, 1 Aug 2016 13:49:29 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 2 Aug 2016 10:23:57 +0200

perf/core: Change log level for duration warning to KERN_INFO

When the perf interrupt handler exceeds a threshold warning messages
are displayed on console:

  [12739.31793] perf interrupt took too long (2504 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
  [71340.165065] perf interrupt took too long (5005 > 5000), lowering kernel.perf_event_max_sample_rate to 25000

Many customers and users are confused by the message wondering if
something is wrong or they need to take action to fix a problem.
Since a user can not do anything to fix the issue, the message is really
more informational than a warning. Adjust the log level accordingly.

Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1470084569-438-1-git-send-email-dsa@cumulusnetworks.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 356a6c7..a19550d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -448,7 +448,7 @@ static u64 __report_allowed;
 
 static void perf_duration_warn(struct irq_work *w)
 {
-	printk_ratelimited(KERN_WARNING
+	printk_ratelimited(KERN_INFO
 		"perf: interrupt took too long (%lld > %lld), lowering "
 		"kernel.perf_event_max_sample_rate to %d\n",
 		__report_avg, __report_allowed,