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Date: Thu, 15 Dec 2016 19:46:46 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: ast@fb.com, lkml <linux-kernel@vger.kernel.org>, acme@kernel.org,
        alexander.shishkin@linux.intel.com, mingo@redhat.com,
        daniel@iogearbox.net, rostedt@goodmis.org,
        Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
        ebiederm@xmission.com, sargun@sargun.me,
        Aravinda Prasad <aravinda@linux.vnet.ibm.com>,
        brendan.d.gregg@gmail.com
Subject: Re: [PATCH v4 1/3] perf: add PERF_RECORD_NAMESPACES to include
 namespaces related info
Message-ID: <20161215184646.GP3107@twins.programming.kicks-ass.net>
References: <148182699546.5314.279803283347257825.stgit@hbathini.in.ibm.com>
 <148182702692.5314.556699668213767056.stgit@hbathini.in.ibm.com>
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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?