RE: [PATCH 1/1] perf/core: fix implicitly enable dynamic interrupt throttle

[Liang, Kan]

> 
> 
> Hmm, would it not be nicer to simply reject the write instead of silently
> ignoring it?
>

Yes, I agree.

Thanks,
Kan

> ---
>  kernel/events/core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c index
> 050a290c72c7..0a51a568d4eb 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -396,6 +396,13 @@ int perf_proc_update_handler(struct ctl_table
> *table, int write,
>  	if (ret || !write)
>  		return ret;
> 
> +	/*
> +	 * If the throttling is disabled; don't allow the write.
> +	 */
> +	if (sysctl_perf_cpu_time_max_percent == 100 ||
> +	    sysctl_perf_cpu_time_max_percent == 0)
> +		return -EINVAL;
> +
>  	max_samples_per_tick =
> DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
>  	perf_sample_period_ns = NSEC_PER_SEC /
> sysctl_perf_event_sample_rate;
>  	update_perf_cpu_limits();