linux-kernel - Re: [PATCH 5/6] perf cs-etm: Use existing decoder instead of resetting it

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Message-ID: <20210719193952.GF2255168@p14s>
Date:   Mon, 19 Jul 2021 13:39:52 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     James Clark <james.clark@....com>
Cc:     acme@...nel.org, coresight@...ts.linaro.org, leo.yan@...aro.org,
        al.grant@....com, branislav.rankov@....com, suzuki.poulose@....com,
        anshuman.khandual@....com, Mike Leach <mike.leach@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] perf cs-etm: Use existing decoder instead of
 resetting it

On Tue, Jul 13, 2021 at 04:40:07PM +0100, James Clark wrote:
> When dumping trace, the decoder is continually deleted and recreated to
> decode each buffer. To support both formatted and unformatted trace in
> a later commit, the decoder will be configured in advance.
> 
> This commit removes the deletion of the decoder and allows the
> formatted/unformatted setting to persist.
> 
> Signed-off-by: James Clark <james.clark@....com>
> ---

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

>  tools/perf/util/cs-etm.c | 37 +++++++------------------------------
>  1 file changed, 7 insertions(+), 30 deletions(-)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 2d07e52ffd3c..760050ea936d 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -508,14 +508,11 @@ static int cs_etm__init_decoder_params(struct cs_etm_decoder_params *d_params,
>  	return ret;
>  }
>  
> -static void cs_etm__dump_event(struct cs_etm_auxtrace *etm,
> +static void cs_etm__dump_event(struct cs_etm_queue *etmq,
>  			       struct auxtrace_buffer *buffer)
>  {
>  	int ret;
>  	const char *color = PERF_COLOR_BLUE;
> -	struct cs_etm_decoder_params d_params;
> -	struct cs_etm_trace_params *t_params;
> -	struct cs_etm_decoder *decoder;
>  	size_t buffer_used = 0;
>  
>  	fprintf(stdout, "\n");
> @@ -523,29 +520,11 @@ static void cs_etm__dump_event(struct cs_etm_auxtrace *etm,
>  		     ". ... CoreSight ETM Trace data: size %zu bytes\n",
>  		     buffer->size);
>  
> -	/* Use metadata to fill in trace parameters for trace decoder */
> -	t_params = zalloc(sizeof(*t_params) * etm->num_cpu);
> -
> -	if (!t_params)
> -		return;
> -
> -	if (cs_etm__init_trace_params(t_params, etm))
> -		goto out_free;
> -
> -	/* Set decoder parameters to simply print the trace packets */
> -	if (cs_etm__init_decoder_params(&d_params, NULL,
> -					CS_ETM_OPERATION_PRINT))
> -		goto out_free;
> -
> -	decoder = cs_etm_decoder__new(etm->num_cpu, &d_params, t_params);
> -
> -	if (!decoder)
> -		goto out_free;
>  	do {
>  		size_t consumed;
>  
>  		ret = cs_etm_decoder__process_data_block(
> -				decoder, buffer->offset,
> +				etmq->decoder, buffer->offset,
>  				&((u8 *)buffer->data)[buffer_used],
>  				buffer->size - buffer_used, &consumed);
>  		if (ret)
> @@ -554,10 +533,7 @@ static void cs_etm__dump_event(struct cs_etm_auxtrace *etm,
>  		buffer_used += consumed;
>  	} while (buffer_used < buffer->size);
>  
> -	cs_etm_decoder__free(decoder);
> -
> -out_free:
> -	zfree(&t_params);
> +	cs_etm_decoder__reset(etmq->decoder);
>  }
>  
>  static int cs_etm__flush_events(struct perf_session *session,
> @@ -769,7 +745,8 @@ static struct cs_etm_queue *cs_etm__alloc_queue(struct cs_etm_auxtrace *etm)
>  
>  	/* Set decoder parameters to decode trace packets */
>  	if (cs_etm__init_decoder_params(&d_params, etmq,
> -					CS_ETM_OPERATION_DECODE))
> +					dump_trace ? CS_ETM_OPERATION_PRINT :
> +						     CS_ETM_OPERATION_DECODE))
>  		goto out_free;
>  
>  	etmq->decoder = cs_etm_decoder__new(etm->num_cpu, &d_params, t_params);
> @@ -2422,7 +2399,7 @@ static void dump_queued_data(struct cs_etm_auxtrace *etm,
>  	for (i = 0; i < etm->queues.nr_queues; ++i)
>  		list_for_each_entry(buf, &etm->queues.queue_array[i].head, list)
>  			if (buf->reference == event->reference)
> -				cs_etm__dump_event(etm, buf);
> +				cs_etm__dump_event(etm->queues.queue_array[i].priv, buf);
>  }
>  
>  static int cs_etm__process_auxtrace_event(struct perf_session *session,
> @@ -2460,7 +2437,7 @@ static int cs_etm__process_auxtrace_event(struct perf_session *session,
>  
>  		if (dump_trace)
>  			if (auxtrace_buffer__get_data(buffer, fd)) {
> -				cs_etm__dump_event(etm, buffer);
> +				cs_etm__dump_event(etm->queues.queue_array[idx].priv, buffer);
>  				auxtrace_buffer__put_data(buffer);
>  			}
>  	} else if (dump_trace)
> -- 
> 2.28.0
>