linux-kernel - Re: [PATCH v3 1/6] perf: add ability to sample machine state on interrupt

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Message-ID: <87bnr7bqx2.fsf@sejong.aot.lge.com>
Date:	Tue, 26 Aug 2014 17:23:21 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	acme@...hat.com, jolsa@...hat.com, dsahern@...il.com
Subject: Re: [PATCH v3 1/6] perf: add ability to sample machine state on interrupt

Hi Stephane,

On Mon, 18 Aug 2014 01:18:15 +0200, Stephane Eranian wrote:
> Enable capture of interrupted machine state for each
> sample.
>
> Registers to sample are passed per event in the
> sample_regs_intr bitmask.
>
> To sample interrupt machine state, the
> PERF_SAMPLE_INTR_REGS must be passed in
> sample_type.
>
> The list of available registers is arch
> dependent and provided by asm/perf_regs.h
>
> Registers are laid out as u64 in the order
> of the bit order of sample_intr_regs.


[SNIP]
> @@ -334,6 +335,15 @@ struct perf_event_attr {
>  
>  	/* Align to u64. */
>  	__u32	__reserved_2;
> +	/*
> +	 * Defines set of regs to dump for each sample
> +	 * state captured on:
> +	 *  - precise = 0: PMU interrupt
> +	 *  - precise > 0: sampled instruction
> +	 *
> +	 * See asm/perf_regs.h for details.
> +	 */
> +	__u64	sample_regs_intr;
>  };

Hmm.. this increases the size of perf_event_attr.  It seems you need to
also define PERF_ATTR_SIZE_VER4 and update attr_file_abi_sizes.

Thanks,
Namhyung
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