linux-kernel - Re: [PATCH 08/37] perf tools: Handle multi-file session properly

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Date:	Wed, 31 Dec 2014 13:01:12 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 08/37] perf tools: Handle multi-file session properly

On Wed, Dec 24, 2014 at 04:15:04PM +0900, Namhyung Kim wrote:
> When perf detects multi-file data directory, process header file first
> and then rest data files in a row.  Note that the multi-file data is
> recorded for each cpu/thread separately, it's already ordered with
> respect to themselves so no need to use the ordered event queue
> interface.
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/data.c    | 17 +++++++++++++++++
>  tools/perf/util/session.c | 41 +++++++++++++++++++++++++++++++----------
>  2 files changed, 48 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
> index 8dacd34659cc..b6f7cdc4a39f 100644
> --- a/tools/perf/util/data.c
> +++ b/tools/perf/util/data.c
> @@ -52,6 +52,21 @@ static int check_backup(struct perf_data_file *file)
>  	return 0;
>  }
>  
> +static void check_multi(struct perf_data_file *file)
> +{
> +	struct stat st;
> +
> +	/*
> +	 * For write, it'll be determined by user (perf record -M)
> +	 * whether to enable multi file data storage.
> +	 */
> +	if (perf_data_file__is_write(file))
> +		return;
> +
> +	if (!stat(file->path, &st) && S_ISDIR(st.st_mode))
> +		file->is_multi = true;
> +}
> +
>  static int scandir_filter(const struct dirent *d)
>  {
>  	return !prefixcmp(d->d_name, "perf.data.");
> @@ -206,6 +221,8 @@ int perf_data_file__open(struct perf_data_file *file)
>  	if (check_pipe(file))
>  		return 0;
>  
> +	check_multi(file);
> +
>  	if (!file->path)
>  		file->path = default_data_path(file);
>  
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 88aa2f09df93..4f0fcd2d3901 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1252,11 +1252,10 @@ fetch_mmaped_event(struct perf_session *session,
>  #define NUM_MMAPS 128
>  #endif
>  
> -static int __perf_session__process_events(struct perf_session *session,
> +static int __perf_session__process_events(struct perf_session *session, int fd,
>  					  u64 data_offset, u64 data_size,
>  					  u64 file_size, struct perf_tool *tool)
>  {
> -	int fd = perf_data_file__fd(session->file);
>  	u64 head, page_offset, file_offset, file_pos, size;
>  	int err, mmap_prot, mmap_flags, map_idx = 0;
>  	size_t	mmap_size;
> @@ -1362,18 +1361,40 @@ int perf_session__process_events(struct perf_session *session,
>  				 struct perf_tool *tool)
>  {
>  	u64 size = perf_data_file__size(session->file);
> -	int err;
> +	int err, i;
>  
>  	if (perf_session__register_idle_thread(session) == NULL)
>  		return -ENOMEM;
>  
> -	if (!perf_data_file__is_pipe(session->file))
> -		err = __perf_session__process_events(session,
> -						     session->header.data_offset,
> -						     session->header.data_size,
> -						     size, tool);
> -	else
> -		err = __perf_session__process_pipe_events(session, tool);
> +	if (perf_data_file__is_pipe(session->file))
> +		return __perf_session__process_pipe_events(session, tool);
> +
> +	err = __perf_session__process_events(session,
> +					     perf_data_file__fd(session->file),
> +					     session->header.data_offset,
> +					     session->header.data_size,
> +					     size, tool);
> +	if (!session->file->is_multi || err)
> +		return err;

if we have file->is_multi true, the perf_data_file__fd(session->file)
is the perf.header file right? So presumably, there's no data in it,
and we dont need to call above __perf_session__process_events function?

jirka

> +
> +	/*
> +	 * For multi-file data storage, events are processed for each
> +	 * cpu/thread so it's already ordered.
> +	 */
> +	tool->ordered_events = false;
> +
> +	for (i = 0; i < session->file->nr_multi; i++) {
> +		int fd = perf_data_file__multi_fd(session->file, i);
> +
> +		size = lseek(fd, 0, SEEK_END);
> +		if (size == 0)
> +			continue;
> +
> +		err = __perf_session__process_events(session, fd,
> +						     0, size, size, tool);
> +		if (err < 0)
> +			break;
> +	}
>  
>  	return err;
>  }
> -- 
> 2.1.3
> 
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