Re: [RFC] perf/core: Add an ioctl to get a number of lost samples

[Andi Kleen]

> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index f5a6a2f069ed..44d72079c77a 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -756,6 +756,8 @@ struct perf_event {
>   	struct pid_namespace		*ns;
>   	u64				id;
>   
> +	atomic_t			lost_samples;

Would rather use atomic64_t. atomic_t might wrap too quickly.

But it might be better to put it somewhere where you already have a lock 
on the event, then you wouldn't need an atomic.

-Andi