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Date:   Mon, 16 Nov 2020 13:39:56 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Namhyung Kim <namhyung@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH v2] perf data: Allow to use stdio functions for pipe mode

Em Sat, Nov 14, 2020 at 09:55:34PM +0100, Jiri Olsa escreveu:
> On Fri, Oct 30, 2020 at 02:47:42PM +0900, Namhyung Kim wrote:
> > When perf data is in a pipe, it reads each event separately using
> > read(2) syscall.  This is a huge performance bottleneck when
> > processing large data like in perf inject.  Also perf inject needs to
> > use write(2) syscall for the output.
> > 
> > So convert it to use buffer I/O functions in stdio library for pipe
> > data.  This makes inject-build-id bench time drops from 20ms to 8ms.
> > 
> >   $ perf bench internals inject-build-id
> >   # Running 'internals/inject-build-id' benchmark:
> >     Average build-id injection took: 8.074 msec (+- 0.013 msec)
> >     Average time per event: 0.792 usec (+- 0.001 usec)
> >     Average memory usage: 8328 KB (+- 0 KB)
> >     Average build-id-all injection took: 5.490 msec (+- 0.008 msec)
> >     Average time per event: 0.538 usec (+- 0.001 usec)
> >     Average memory usage: 7563 KB (+- 0 KB)
> > 
> > This patch enables it just for perf inject when used with pipe (it's a
> > default behavior).  Maybe we could do it for perf record and/or report
> > later..
> > 
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> 
> Acked-by: Jiri Olsa <jolsa@...hat.com>

Thanks, tested and applied.

- Arnaldo
 
> thanks,
> jirka
> 
> > ---
> > v2: check result of fdopen()
> > 
> >  tools/perf/builtin-inject.c |  2 ++
> >  tools/perf/util/data.c      | 41 ++++++++++++++++++++++++++++++++++---
> >  tools/perf/util/data.h      | 11 +++++++++-
> >  tools/perf/util/header.c    |  8 ++++----
> >  tools/perf/util/session.c   |  7 ++++---
> >  5 files changed, 58 insertions(+), 11 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> > index 452a75fe68e5..14d6c88fed76 100644
> > --- a/tools/perf/builtin-inject.c
> > +++ b/tools/perf/builtin-inject.c
> > @@ -853,10 +853,12 @@ int cmd_inject(int argc, const char **argv)
> >  		.output = {
> >  			.path = "-",
> >  			.mode = PERF_DATA_MODE_WRITE,
> > +			.use_stdio = true,
> >  		},
> >  	};
> >  	struct perf_data data = {
> >  		.mode = PERF_DATA_MODE_READ,
> > +		.use_stdio = true,
> >  	};
> >  	int ret;
> >  
> > diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
> > index c47aa34fdc0a..05bbcb663c41 100644
> > --- a/tools/perf/util/data.c
> > +++ b/tools/perf/util/data.c
> > @@ -174,8 +174,21 @@ static bool check_pipe(struct perf_data *data)
> >  			is_pipe = true;
> >  	}
> >  
> > -	if (is_pipe)
> > -		data->file.fd = fd;
> > +	if (is_pipe) {
> > +		if (data->use_stdio) {
> > +			const char *mode;
> > +
> > +			mode = perf_data__is_read(data) ? "r" : "w";
> > +			data->file.fptr = fdopen(fd, mode);
> > +
> > +			if (data->file.fptr == NULL) {
> > +				data->file.fd = fd;
> > +				data->use_stdio = false;
> > +			}
> > +		} else {
> > +			data->file.fd = fd;
> > +		}
> > +	}
> >  
> >  	return data->is_pipe = is_pipe;
> >  }
> > @@ -334,6 +347,9 @@ int perf_data__open(struct perf_data *data)
> >  	if (check_pipe(data))
> >  		return 0;
> >  
> > +	/* currently it allows stdio for pipe only */
> > +	data->use_stdio = false;
> > +
> >  	if (!data->path)
> >  		data->path = "perf.data";
> >  
> > @@ -353,7 +369,21 @@ void perf_data__close(struct perf_data *data)
> >  		perf_data__close_dir(data);
> >  
> >  	zfree(&data->file.path);
> > -	close(data->file.fd);
> > +
> > +	if (data->use_stdio)
> > +		fclose(data->file.fptr);
> > +	else
> > +		close(data->file.fd);
> > +}
> > +
> > +ssize_t perf_data__read(struct perf_data *data, void *buf, size_t size)
> > +{
> > +	if (data->use_stdio) {
> > +		if (fread(buf, size, 1, data->file.fptr) == 1)
> > +			return size;
> > +		return feof(data->file.fptr) ? 0 : -1;
> > +	}
> > +	return readn(data->file.fd, buf, size);
> >  }
> >  
> >  ssize_t perf_data_file__write(struct perf_data_file *file,
> > @@ -365,6 +395,11 @@ ssize_t perf_data_file__write(struct perf_data_file *file,
> >  ssize_t perf_data__write(struct perf_data *data,
> >  			      void *buf, size_t size)
> >  {
> > +	if (data->use_stdio) {
> > +		if (fwrite(buf, size, 1, data->file.fptr) == 1)
> > +			return size;
> > +		return -1;
> > +	}
> >  	return perf_data_file__write(&data->file, buf, size);
> >  }
> >  
> > diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
> > index 75947ef6bc17..c563fcbb0288 100644
> > --- a/tools/perf/util/data.h
> > +++ b/tools/perf/util/data.h
> > @@ -2,6 +2,7 @@
> >  #ifndef __PERF_DATA_H
> >  #define __PERF_DATA_H
> >  
> > +#include <stdio.h>
> >  #include <stdbool.h>
> >  
> >  enum perf_data_mode {
> > @@ -16,7 +17,10 @@ enum perf_dir_version {
> >  
> >  struct perf_data_file {
> >  	char		*path;
> > -	int		 fd;
> > +	union {
> > +		int	 fd;
> > +		FILE	*fptr;
> > +	};
> >  	unsigned long	 size;
> >  };
> >  
> > @@ -26,6 +30,7 @@ struct perf_data {
> >  	bool			 is_pipe;
> >  	bool			 is_dir;
> >  	bool			 force;
> > +	bool			 use_stdio;
> >  	enum perf_data_mode	 mode;
> >  
> >  	struct {
> > @@ -62,11 +67,15 @@ static inline bool perf_data__is_single_file(struct perf_data *data)
> >  
> >  static inline int perf_data__fd(struct perf_data *data)
> >  {
> > +	if (data->use_stdio)
> > +		return fileno(data->file.fptr);
> > +
> >  	return data->file.fd;
> >  }
> >  
> >  int perf_data__open(struct perf_data *data);
> >  void perf_data__close(struct perf_data *data);
> > +ssize_t perf_data__read(struct perf_data *data, void *buf, size_t size);
> >  ssize_t perf_data__write(struct perf_data *data,
> >  			      void *buf, size_t size);
> >  ssize_t perf_data_file__write(struct perf_data_file *file,
> > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> > index be850e9f8852..d9a70154426b 100644
> > --- a/tools/perf/util/header.c
> > +++ b/tools/perf/util/header.c
> > @@ -3652,7 +3652,8 @@ static int perf_file_section__process(struct perf_file_section *section,
> >  }
> >  
> >  static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,
> > -				       struct perf_header *ph, int fd,
> > +				       struct perf_header *ph,
> > +				       struct perf_data* data,
> >  				       bool repipe)
> >  {
> >  	struct feat_fd ff = {
> > @@ -3661,7 +3662,7 @@ static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,
> >  	};
> >  	ssize_t ret;
> >  
> > -	ret = readn(fd, header, sizeof(*header));
> > +	ret = perf_data__read(data, header, sizeof(*header));
> >  	if (ret <= 0)
> >  		return -1;
> >  
> > @@ -3684,8 +3685,7 @@ static int perf_header__read_pipe(struct perf_session *session)
> >  	struct perf_header *header = &session->header;
> >  	struct perf_pipe_file_header f_header;
> >  
> > -	if (perf_file_header__read_pipe(&f_header, header,
> > -					perf_data__fd(session->data),
> > +	if (perf_file_header__read_pipe(&f_header, header, session->data,
> >  					session->repipe) < 0) {
> >  		pr_debug("incompatible file format\n");
> >  		return -EINVAL;
> > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> > index 7a5f03764702..f901a09a58e4 100644
> > --- a/tools/perf/util/session.c
> > +++ b/tools/perf/util/session.c
> > @@ -1923,7 +1923,6 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> >  {
> >  	struct ordered_events *oe = &session->ordered_events;
> >  	struct perf_tool *tool = session->tool;
> > -	int fd = perf_data__fd(session->data);
> >  	union perf_event *event;
> >  	uint32_t size, cur_size = 0;
> >  	void *buf = NULL;
> > @@ -1943,7 +1942,8 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> >  	ordered_events__set_copy_on_queue(oe, true);
> >  more:
> >  	event = buf;
> > -	err = readn(fd, event, sizeof(struct perf_event_header));
> > +	err = perf_data__read(session->data, event,
> > +			      sizeof(struct perf_event_header));
> >  	if (err <= 0) {
> >  		if (err == 0)
> >  			goto done;
> > @@ -1975,7 +1975,8 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> >  	p += sizeof(struct perf_event_header);
> >  
> >  	if (size - sizeof(struct perf_event_header)) {
> > -		err = readn(fd, p, size - sizeof(struct perf_event_header));
> > +		err = perf_data__read(session->data, p,
> > +				      size - sizeof(struct perf_event_header));
> >  		if (err <= 0) {
> >  			if (err == 0) {
> >  				pr_err("unexpected end of event stream\n");
> > -- 
> > 2.29.1.341.ge80a0c044ae-goog
> > 
> 

-- 

- Arnaldo

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