Re: [PATCH v9 06/14] perf: Add AUX record

[Jiri Olsa]

On Wed, Jan 14, 2015 at 02:18:15PM +0200, Alexander Shishkin wrote:
> When there's new data in the AUX space, output a record indicating its
> offset and size and a set of flags, such as PERF_AUX_FLAG_TRUNCATED, to
> mean the described data was truncated to fit in the ring buffer.
> 
> Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxx>
> ---
>  include/uapi/linux/perf_event.h | 19 +++++++++++++++++++
>  kernel/events/core.c            | 34 ++++++++++++++++++++++++++++++++++
>  kernel/events/internal.h        |  3 +++
>  3 files changed, 56 insertions(+)
> 
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index b7ccdf5e93..2d40e2aa07 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -746,6 +746,20 @@ enum perf_event_type {
>  	 */
>  	PERF_RECORD_MMAP2			= 10,
>  
> +	/*
> +	 * Records that new data landed in the AUX buffer part.
> +	 *
> +	 * struct {
> +	 * 	struct perf_event_header	header;
> +	 *
> +	 * 	u64				aux_offset;
> +	 * 	u64				aux_size;
> +	 *	u64				flags;
> +	 * 	struct sample_id		sample_id;

hum, I dont see sample_id below in implementation

jirka

> +	 * };
> +	 */
> +	PERF_RECORD_AUX				= 11,
> +
>  	PERF_RECORD_MAX,			/* non-ABI */
>  };
>  
> @@ -763,6 +777,11 @@ enum perf_callchain_context {
>  	PERF_CONTEXT_MAX		= (__u64)-4095,
>  };
>  
> +/**
> + * PERF_RECORD_AUX::flags bits
> + */
> +#define PERF_AUX_FLAG_TRUNCATED		0x01	/* record was truncated to fit */
> +
>  #define PERF_FLAG_FD_NO_GROUP		(1UL << 0)
>  #define PERF_FLAG_FD_OUTPUT		(1UL << 1)
>  #define PERF_FLAG_PID_CGROUP		(1UL << 2) /* pid=cgroup id, per-cpu mode only */
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index a6a145ad0b..4e17393264 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -5648,6 +5648,40 @@ void perf_event_mmap(struct vm_area_struct *vma)
>  	perf_event_mmap_event(&mmap_event);
>  }
>  
> +void perf_event_aux_event(struct perf_event *event, unsigned long head,
> +			  unsigned long size, u64 flags)
> +{
> +	struct perf_output_handle handle;
> +	struct perf_sample_data sample;
> +	struct perf_aux_event {
> +		struct perf_event_header	header;
> +		u64				offset;
> +		u64				size;
> +		u64				flags;
> +	} rec = {
> +		.header = {
> +			.type = PERF_RECORD_AUX,
> +			.misc = 0,
> +			.size = sizeof(rec),
> +		},
> +		.offset		= head,
> +		.size		= size,
> +		.flags		= flags,
> +	};
> +	int ret;
> +
> +	perf_event_header__init_id(&rec.header, &sample, event);
> +	ret = perf_output_begin(&handle, event, rec.header.size);
> +
> +	if (ret)
> +		return;
> +
> +	perf_output_put(&handle, rec);
> +	perf_event__output_id_sample(event, &handle, &sample);
> +
> +	perf_output_end(&handle);
> +}
> +
>  /*
>   * IRQ throttle logging
>   */
> diff --git a/kernel/events/internal.h b/kernel/events/internal.h
> index 0f6d080159..4d117a9814 100644
> --- a/kernel/events/internal.h
> +++ b/kernel/events/internal.h
> @@ -62,6 +62,9 @@ static inline bool rb_has_aux(struct ring_buffer *rb)
>  	return !!rb->aux_nr_pages;
>  }
>  
> +void perf_event_aux_event(struct perf_event *event, unsigned long head,
> +			  unsigned long size, u64 flags);
> +
>  extern void
>  perf_event_header__init_id(struct perf_event_header *header,
>  			   struct perf_sample_data *data,
> -- 
> 2.1.4
> 
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