Re: [PATCH 6/6] perf session: Load single file for analysis

[Jiri Olsa <jolsa@redhat.com>]

On Wed, Sep 29, 2021 at 11:41:54AM +0300, Alexey Bayduraev wrote:
> Adding EOF flag to reader state and moving the check to reader__mmap.
> Separating reading code of single event into reader__read_event function.
> Adding basic reader return codes to simplify the code and introducing
> remap/read_event loop in __perf_session__process_events.
> 
> Suggested-by: Jiri Olsa <jolsa@kernel.org>
> Acked-by: Namhyung Kim <namhyung@gmail.com>
> Reviewed-by: Riccardo Mancini <rickyman7@gmail.com>
> Tested-by: Riccardo Mancini <rickyman7@gmail.com>
> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
> ---
>  tools/perf/util/session.c | 72 ++++++++++++++++++++++++---------------
>  1 file changed, 45 insertions(+), 27 deletions(-)
> 
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 5e08def72b41..9a4fe78a7a54 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -63,6 +63,13 @@ struct reader_state {
>  	u64	 file_offset;
>  	u64	 data_size;
>  	u64	 head;
> +	bool	 eof;

what's this flag for? I can't see it being used

jirka

> +};
> +
> +enum {
> +	READER_EOF,
> +	READER_NODATA,
> +	READER_OK,
>  };
>  
>  struct reader {
> @@ -2242,6 +2249,11 @@ reader__mmap(struct reader *rd, struct perf_session *session)
>  	char *buf, **mmaps = st->mmaps;
>  	u64 page_offset;
>  
> +	if (st->file_pos >= st->data_size) {
> +		st->eof = true;
> +		return READER_EOF;
> +	}
> +
>  	mmap_prot  = PROT_READ;
>  	mmap_flags = MAP_SHARED;
>  
> @@ -2270,36 +2282,26 @@ reader__mmap(struct reader *rd, struct perf_session *session)
>  	mmaps[st->mmap_idx] = st->mmap_cur = buf;
>  	st->mmap_idx = (st->mmap_idx + 1) & (ARRAY_SIZE(st->mmaps) - 1);
>  	st->file_pos = st->file_offset + st->head;
> -	return 0;
> +	return READER_OK;
>  }
>  
>  static int
> -reader__process_events(struct reader *rd, struct perf_session *session,
> -		       struct ui_progress *prog)
> +reader__read_event(struct reader *rd, struct perf_session *session,
> +		   struct ui_progress *prog)
>  {
>  	struct reader_state *st = &rd->state;
> -	u64 size;
> -	int err = 0;
> +	int err = READER_OK;
>  	union perf_event *event;
> +	u64 size;
>  	s64 skip;
>  
> -remap:
> -	err = reader__mmap(rd, session);
> -	if (err)
> -		goto out;
> -	if (session->one_mmap) {
> -		session->one_mmap_addr   = rd->state.mmap_cur;
> -		session->one_mmap_offset = rd->state.file_offset;
> -	}
> -
> -more:
>  	event = fetch_mmaped_event(st->head, st->mmap_size, st->mmap_cur,
>  				   session->header.needs_swap);
>  	if (IS_ERR(event))
>  		return PTR_ERR(event);
>  
>  	if (!event)
> -		goto remap;
> +		return READER_NODATA;
>  
>  	session->active_reader = rd;
>  	size = event->header.size;
> @@ -2321,18 +2323,12 @@ reader__process_events(struct reader *rd, struct perf_session *session,
>  	st->head += size;
>  	st->file_pos += size;
>  
> -	err = __perf_session__process_decomp_events(session);
> -	if (err)
> -		goto out;
> +	skip = __perf_session__process_decomp_events(session);
> +	if (skip)
> +		err = skip;
>  
>  	ui_progress__update(prog, size);
>  
> -	if (session_done())
> -		goto out;
> -
> -	if (st->file_pos < st->data_size)
> -		goto more;
> -
>  out:
>  	session->active_reader = NULL;
>  	return err;
> @@ -2369,9 +2365,31 @@ static int __perf_session__process_events(struct perf_session *session)
>  	err = reader__init(&rd, &session->one_mmap);
>  	if (err)
>  		goto out_err;
> -	err = reader__process_events(&rd, session, &prog);
> -	if (err)
> +	err = reader__mmap(&rd, session);
> +	if (err != READER_OK) {
> +		if (err == READER_EOF)
> +			err = -EINVAL;
>  		goto out_err;
> +	}
> +	if (session->one_mmap) {
> +		session->one_mmap_addr   = rd.state.mmap_cur;
> +		session->one_mmap_offset = rd.state.file_offset;
> +	}
> +
> +	while (true) {
> +		if (session_done())
> +			break;
> +
> +		err = reader__read_event(&rd, session, &prog);
> +		if (err < 0)
> +			break;
> +		if (err == READER_NODATA) {
> +			err = reader__mmap(&rd, session);
> +			if (err <= 0)
> +				break;
> +		}
> +	}
> +
>  	/* do the final flush for ordered samples */
>  	err = ordered_events__flush(oe, OE_FLUSH__FINAL);
>  	if (err)
> -- 
> 2.19.0
>