Re: [PATCH v4 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Dec 16, 2016 at 12:07:06AM +0530, Hari Bathini wrote:
> +struct perf_ns_link_info {
> +	__u64	dev;
> +	__u64	ino;
> +};
> +
> +enum {
> +	NET_NS_INDEX		= 0,
> +	UTS_NS_INDEX		= 1,
> +	IPC_NS_INDEX		= 2,
> +	PID_NS_INDEX		= 3,
> +	USER_NS_INDEX		= 4,
> +	MNT_NS_INDEX		= 5,
> +	CGROUP_NS_INDEX		= 6,
> +
> +	NAMESPACES_MAX,		/* maximum available namespaces */
> +};
> +
>  enum perf_event_type {
>  
>  	/*
> @@ -862,6 +880,17 @@ enum perf_event_type {
>  	 */
>  	PERF_RECORD_SWITCH_CPU_WIDE		= 15,
>  
> +	/*
> +	 * struct {
> +	 *	struct perf_event_header	header;
> +	 *	u32				pid;
> +	 *	u32				tid;
> +	 *	struct namespace_link_info	link_info[NAMESPACES_MAX];
> +	 *	struct sample_id		sample_id;
> +	 * };
> +	 */
> +	PERF_RECORD_NAMESPACES			= 16,
> +
>  	PERF_RECORD_MAX,			/* non-ABI */
>  };

What happens if a future kernel adds another namespace?