perf/core: Make sysctl_perf_cpu_time_max_percent conform to documentation

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

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 91a612eea9a3 ("perf/core: Fix dynamic interrupt throttle")
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 52bedc5a5aaa190be3545d7534ce065ce735e473..2c78b6f473395e952706726d9a622d8eff1bc766 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -412,7 +412,8 @@ 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);