Messages in this thread Patch in this message | | | Date | Sat, 2 Apr 2016 13:00:17 +0200 | From | Peter Zijlstra <> | Subject | Re: "perf: interrupt took too long" messages even with perf_cpu_time_max_percent==0 |
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On Sat, Apr 02, 2016 at 11:32:39AM +0200, Markus Trippelsdorf wrote: > Current git kernel sometimes shows: > > perf: interrupt took too long (71 > 52), lowering kernel.perf_event_max_sample_rate to 300 > perf: interrupt took too long (103 > 88), lowering kernel.perf_event_max_sample_rate to 300 > perf: interrupt took too long (130 > 128), lowering kernel.perf_event_max_sample_rate to 300 > perf: interrupt took too long (175 > 162), lowering kernel.perf_event_max_sample_rate to 300 > perf: interrupt took too long (219 > 218), lowering kernel.perf_event_max_sample_rate to 300 > ... > > when running e.g. "perf top" even when > /proc/sys/kernel/perf_cpu_time_max_percent is set to 0.
Ah, was 0 also meant to disable it?
Does the below help?
--- 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 8c3b35f2a269..21ba024c9ed1 100644 --- 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);
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