Re: [BUG] perf stat: explicit grouping yields unexpected results

[Andi Kleen <ak@linux.intel.com>]

> Something like below? user space supply buffer for error string.

That would work, although I was thinking of making it a more
generic mechanism (store it into task_struct, have a extra
syscall to retrieve)

-Andi

> 
> jirka
> 
> 
> ---
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index e1802d6..a827870 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -331,8 +331,8 @@ struct perf_event_attr {
>  	 */
>  	__u32	sample_stack_user;
>  
> -	/* Align to u64. */
> -	__u32	__reserved_2;
> +	__u32	errstr_size;
> +	char	*errstr;
>  };
>  
>  #define perf_flags(attr)	(*(&(attr)->read_format + 1))
> 

-- 
ak@linux.intel.com -- Speaking for myself only