perf data: Allow to use stdio functions for pipe mode

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..

Committer testing:

Before:

  $ perf stat -r 5 perf bench internals inject-build-id
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 13.605 msec (+- 0.064 msec)
    Average time per event: 1.334 usec (+- 0.006 usec)
    Average memory usage: 12220 KB (+- 7 KB)
    Average build-id-all injection took: 11.458 msec (+- 0.058 msec)
    Average time per event: 1.123 usec (+- 0.006 usec)
    Average memory usage: 11546 KB (+- 8 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 13.673 msec (+- 0.057 msec)
    Average time per event: 1.341 usec (+- 0.006 usec)
    Average memory usage: 12508 KB (+- 8 KB)
    Average build-id-all injection took: 11.437 msec (+- 0.046 msec)
    Average time per event: 1.121 usec (+- 0.004 usec)
    Average memory usage: 11812 KB (+- 7 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 13.641 msec (+- 0.069 msec)
    Average time per event: 1.337 usec (+- 0.007 usec)
    Average memory usage: 12302 KB (+- 8 KB)
    Average build-id-all injection took: 10.820 msec (+- 0.106 msec)
    Average time per event: 1.061 usec (+- 0.010 usec)
    Average memory usage: 11616 KB (+- 7 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 13.379 msec (+- 0.074 msec)
    Average time per event: 1.312 usec (+- 0.007 usec)
    Average memory usage: 12334 KB (+- 8 KB)
    Average build-id-all injection took: 11.288 msec (+- 0.071 msec)
    Average time per event: 1.107 usec (+- 0.007 usec)
    Average memory usage: 11657 KB (+- 8 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 13.534 msec (+- 0.058 msec)
    Average time per event: 1.327 usec (+- 0.006 usec)
    Average memory usage: 12264 KB (+- 8 KB)
    Average build-id-all injection took: 11.557 msec (+- 0.076 msec)
    Average time per event: 1.133 usec (+- 0.007 usec)
    Average memory usage: 11593 KB (+- 8 KB)

   Performance counter stats for 'perf bench internals inject-build-id' (5 runs):

            4,060.05 msec task-clock:u              #    1.566 CPUs utilized            ( +-  0.65% )
                   0      context-switches:u        #    0.000 K/sec
                   0      cpu-migrations:u          #    0.000 K/sec
             101,888      page-faults:u             #    0.025 M/sec                    ( +-  0.12% )
       3,745,833,163      cycles:u                  #    0.923 GHz                      ( +-  0.10% )  (83.22%)
         194,346,613      stalled-cycles-frontend:u #    5.19% frontend cycles idle     ( +-  0.57% )  (83.30%)
         708,495,034      stalled-cycles-backend:u  #   18.91% backend cycles idle      ( +-  0.48% )  (83.48%)
       5,629,328,628      instructions:u            #    1.50  insn per cycle
                                                    #    0.13  stalled cycles per insn  ( +-  0.21% )  (83.57%)
       1,236,697,927      branches:u                #  304.602 M/sec                    ( +-  0.16% )  (83.44%)
          17,564,877      branch-misses:u           #    1.42% of all branches          ( +-  0.23% )  (82.99%)

              2.5934 +- 0.0128 seconds time elapsed  ( +-  0.49% )

  $

After:

  $ perf stat -r 5 perf bench internals inject-build-id
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 8.560 msec (+- 0.125 msec)
    Average time per event: 0.839 usec (+- 0.012 usec)
    Average memory usage: 12520 KB (+- 8 KB)
    Average build-id-all injection took: 5.789 msec (+- 0.054 msec)
    Average time per event: 0.568 usec (+- 0.005 usec)
    Average memory usage: 11919 KB (+- 9 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 8.639 msec (+- 0.111 msec)
    Average time per event: 0.847 usec (+- 0.011 usec)
    Average memory usage: 12732 KB (+- 8 KB)
    Average build-id-all injection took: 5.647 msec (+- 0.069 msec)
    Average time per event: 0.554 usec (+- 0.007 usec)
    Average memory usage: 12093 KB (+- 7 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 8.551 msec (+- 0.096 msec)
    Average time per event: 0.838 usec (+- 0.009 usec)
    Average memory usage: 12739 KB (+- 8 KB)
    Average build-id-all injection took: 5.617 msec (+- 0.061 msec)
    Average time per event: 0.551 usec (+- 0.006 usec)
    Average memory usage: 12105 KB (+- 7 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 8.403 msec (+- 0.097 msec)
    Average time per event: 0.824 usec (+- 0.010 usec)
    Average memory usage: 12770 KB (+- 8 KB)
    Average build-id-all injection took: 5.611 msec (+- 0.085 msec)
    Average time per event: 0.550 usec (+- 0.008 usec)
    Average memory usage: 12134 KB (+- 8 KB)
  # Running 'internals/inject-build-id' benchmark:
    Average build-id injection took: 8.518 msec (+- 0.102 msec)
    Average time per event: 0.835 usec (+- 0.010 usec)
    Average memory usage: 12518 KB (+- 10 KB)
    Average build-id-all injection took: 5.503 msec (+- 0.073 msec)
    Average time per event: 0.540 usec (+- 0.007 usec)
    Average memory usage: 11882 KB (+- 8 KB)

   Performance counter stats for 'perf bench internals inject-build-id' (5 runs):

            2,394.88 msec task-clock:u              #    1.577 CPUs utilized            ( +-  0.83% )
                   0      context-switches:u        #    0.000 K/sec
                   0      cpu-migrations:u          #    0.000 K/sec
             103,181      page-faults:u             #    0.043 M/sec                    ( +-  0.11% )
       3,548,172,030      cycles:u                  #    1.482 GHz                      ( +-  0.30% )  (83.26%)
          81,537,700      stalled-cycles-frontend:u #    2.30% frontend cycles idle     ( +-  1.54% )  (83.24%)
         876,631,544      stalled-cycles-backend:u  #   24.71% backend cycles idle      ( +-  1.14% )  (83.45%)
       5,960,361,707      instructions:u            #    1.68  insn per cycle
                                                    #    0.15  stalled cycles per insn  ( +-  0.27% )  (83.26%)
       1,269,413,491      branches:u                #  530.054 M/sec                    ( +-  0.10% )  (83.48%)
          11,372,453      branch-misses:u           #    0.90% of all branches          ( +-  0.52% )  (83.31%)

             1.51874 +- 0.00642 seconds time elapsed  ( +-  0.42% )

  $
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201030054742.87740-1-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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;
 

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);
 }
 

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,

tools/perf/util/header.c

@@ -3647,7 +3647,8 @@ 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 = {
@@ -3656,7 +3657,7 @@ 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;
 
@@ -3679,8 +3680,7 @@ 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;

tools/perf/util/session.c

@@ -1937,7 +1937,6 @@ 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;
@@ -1957,7 +1956,8 @@ 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;
@@ -1989,7 +1989,8 @@ 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");