linux-kernel - [PATCH -stable 4.1 3/4] perf/core: Make sysctl_perf_cpu_time_max

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Message-ID: <1488784465-58402-4-git-send-email-tanxiaojun@huawei.com>
Date:   Mon, 6 Mar 2017 15:14:24 +0800
From:   Tan Xiaojun <tanxiaojun@...wei.com>
To:     <alexander.levin@...izon.com>, <peterz@...radead.org>,
        <wangnan0@...wei.com>, <guohanjun@...wei.com>
CC:     <linuxarm@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH -stable 4.1 3/4] perf/core: Make sysctl_perf_cpu_time_max_percent conform to documentation

From: Peter Zijlstra <peterz@...radead.org>

Markus reported that 0 should also disable the throttling we per
Documentation/sysctl/kernel.txt.

Reported-by: Markus Trippelsdorf <markus@...ppelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
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: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Fixes: 91a612eea9a3 ("perf/core: Fix dynamic interrupt throttle")
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Tan Xiaojun <tanxiaojun@...wei.com>
---
 kernel/events/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f96ad76..350c45a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -241,7 +241,8 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 	if (ret || !write)
 		return ret;
 
-	if (sysctl_perf_cpu_time_max_percent == 100) {
+	if (sysctl_perf_cpu_time_max_percent == 100 ||
+	    sysctl_perf_cpu_time_max_percent == 0) {
 		printk(KERN_WARNING
 		       "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
 		WRITE_ONCE(perf_sample_allowed_ns, 0);
-- 
1.9.1