linux-kernel - Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD

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Message-ID: <20161123201317.GB3092@twins.programming.kicks-ass.net>
Date:   Wed, 23 Nov 2016 21:13:17 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...el.com
Cc:     mingo@...hat.com, acme@...nel.org, linux-kernel@...r.kernel.org,
        alexander.shishkin@...ux.intel.com, tglx@...utronix.de,
        namhyung@...nel.org, jolsa@...nel.org, adrian.hunter@...el.com,
        wangnan0@...wei.com, mark.rutland@....com, andi@...stfloor.org
Subject: Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD

On Wed, Nov 23, 2016 at 04:44:39AM -0500, kan.liang@...el.com wrote:
> +/*
> + * single overhead record layout:
> + *
> + * 	 cpu: The cpu which overhead occues

This is duplicate information, its already present in sample_id when
PERF_SAMPLE_CPU, and without that we don't care.

> + * 	  nr: Times of overhead happens.
> + * 	      E.g. for NMI, nr == times of NMI handler are called.
> + * 	time: Total overhead cost(ns)
> + */
> +struct perf_overhead_entry {
> +	__u32	cpu;
> +	__u64	nr;
> +	__u64	time;
> +};