linux-kernel - Re: [PATCH 1/4] perf: add ability to sample machine state on interrupt

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Date:	Wed, 9 Jul 2014 12:03:29 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	ak@...ux.intel.com, jolsa@...hat.com, namhyung@...nel.org
Subject: Re: [PATCH 1/4] perf: add ability to sample machine state on
 interrupt

Em Wed, Jul 09, 2014 at 12:15:56AM +0200, Stephane Eranian escreveu:
> Enable capture of interrupted machine state in 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.

I would have broken this into smaller pieces, with the first patch doing
the prep of renaming perf_regs_user to perf_regs, for instance.
 
> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> ---
>  include/linux/perf_event.h      |  7 +++++--
>  include/uapi/linux/perf_event.h | 14 ++++++++++++-
>  kernel/events/core.c            | 44 +++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 60 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 707617a..4970c1d 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -78,7 +78,7 @@ struct perf_branch_stack {
>  	struct perf_branch_entry	entries[0];
>  };
>  
> -struct perf_regs_user {
> +struct perf_regs {
>  	__u64		abi;
>  	struct pt_regs	*regs;
>  };
> @@ -595,7 +595,8 @@ struct perf_sample_data {
>  	struct perf_callchain_entry	*callchain;
>  	struct perf_raw_record		*raw;
>  	struct perf_branch_stack	*br_stack;
> -	struct perf_regs_user		regs_user;
> +	struct perf_regs		regs_user;
> +	struct perf_regs		regs_intr;
>  	u64				stack_user_size;
>  	u64				weight;
>  	/*
> @@ -618,6 +619,8 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
>  	data->weight = 0;
>  	data->data_src.val = 0;
>  	data->txn = 0;
> +	data->regs_intr.abi = PERF_SAMPLE_REGS_ABI_NONE;
> +	data->regs_intr.regs = NULL;

Nit:

This would be better right after the equivalent ones for regs_user, I
had to go to perf_sample_data_init() to check if that was done, yes, it
is right before data->weight = 0 :-)

Reading on...
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