[PATCH v2 0/2] perf test: Display remaining tests while waiting

[PATCH v2 0/2] perf test: Display remaining tests while waiting

[Ian Rogers]

The v1 patch series:
https://lore.kernel.org/lkml/20240405070931.1231245-1-irogers@google.com/
was partially merged. The check_if_command_finished wasn't working as
intended as stdout/stderr could be lost due to waitpid being
called. Modify this function to not use waitpid and use procfs
instead.

Keeping the output test display logic in 1 place should simplify
improving parallel and sequential output. Namhyung was experiencing
issues with this in:
https://lore.kernel.org/lkml/20240628215751.1512250-1-namhyung@kernel.org/

Ian Rogers (2):
  tools subcmd: Add non-waitpid check_if_command_finished()
  perf test: Display number of remaining tests

 tools/lib/subcmd/run-command.c  | 33 ++++++++++++++
 tools/perf/tests/builtin-test.c | 77 ++++++++++++++++++++++-----------
 tools/perf/util/color.h         |  1 +
 3 files changed, 86 insertions(+), 25 deletions(-)

-- 
2.45.2.803.g4e1b14247a-goog

[PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Ian Rogers]

Using waitpid can cause stdout/stderr of the child process to be
lost. Use Linux's /prod/<pid>/status file to determine if the process
has reached the zombie state. Use the 'status' file rather than 'stat'
to avoid issues around skipping the process name.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
index 4e3a557a2f37..ec06683e77a0 100644
--- a/tools/lib/subcmd/run-command.c
+++ b/tools/lib/subcmd/run-command.c
@@ -2,6 +2,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <ctype.h>
 #include <fcntl.h>
 #include <string.h>
 #include <linux/string.h>
@@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
 
 int check_if_command_finished(struct child_process *cmd)
 {
+#ifdef __linux__
+	char filename[FILENAME_MAX + 12];
+	char status_line[256];
+	FILE *status_file;
+
+	/*
+	 * Check by reading /proc/<pid>/status as calling waitpid causes
+	 * stdout/stderr to be closed and data lost.
+	 */
+	sprintf(filename, "/proc/%d/status", cmd->pid);
+	status_file = fopen(filename, "r");
+	if (status_file == NULL) {
+		/* Open failed assume finish_command was called. */
+		return true;
+	}
+	while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
+		char *p;
+
+		if (strncmp(status_line, "State:", 6))
+			continue;
+
+		fclose(status_file);
+		p = status_line + 6;
+		while (isspace(*p))
+			p++;
+		return *p == 'Z';
+	}
+	/* Read failed assume finish_command was called. */
+	fclose(status_file);
+	return true;
+#else
 	wait_or_whine(cmd, /*block=*/false);
 	return cmd->finished;
+#endif
 }
 
 int finish_command(struct child_process *cmd)
-- 
2.45.2.803.g4e1b14247a-goog

[PATCH v2 2/2] perf test: Display number of remaining tests

[Ian Rogers]

Before polling or sleeping to wait for a test to complete, print out
": Running (<num> remaining)" where the number of remaining tests is
determined by iterating over the remaining tests and seeing which
return true for check_if_command_finished. After the delay, erase the
line and either update it with the new number of remaining tests, or
print the test's result. This allows a user to know a test is running
and in parallel mode (default) how many of the tests are waiting to
complete. If color mode is disabled then avoid displaying the
"Running" message.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/builtin-test.c | 77 ++++++++++++++++++++++-----------
 tools/perf/util/color.h         |  1 +
 2 files changed, 53 insertions(+), 25 deletions(-)

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index c3d84b67ca8e..23be9139f229 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -241,7 +241,10 @@ static int run_test_child(struct child_process *process)
 	return -err;
 }
 
-static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
+#define TEST_RUNNING -3
+
+static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
+			     int remaining)
 {
 	if (has_subtests(t)) {
 		int subw = width > 2 ? width - 2 : width;
@@ -251,6 +254,9 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
 		pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
 
 	switch (result) {
+	case TEST_RUNNING:
+		color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d remaining)\n", remaining);
+		break;
 	case TEST_OK:
 		pr_info(" Ok\n");
 		break;
@@ -272,13 +278,15 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
 	return 0;
 }
 
-static int finish_test(struct child_test *child_test, int width)
+static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
+		       int width)
 {
+	struct child_test *child_test = child_tests[running_test];
 	struct test_suite *t = child_test->test;
 	int i = child_test->test_num;
 	int subi = child_test->subtest;
 	int err = child_test->process.err;
-	bool err_done = err <= 0;
+	bool err_done = false;
 	struct strbuf err_output = STRBUF_INIT;
 	int ret;
 
@@ -293,7 +301,7 @@ static int finish_test(struct child_test *child_test, int width)
 	 * Busy loop reading from the child's stdout/stderr that are set to be
 	 * non-blocking until EOF.
 	 */
-	if (!err_done)
+	if (err > 0)
 		fcntl(err, F_SETFL, O_NONBLOCK);
 	if (verbose > 1) {
 		if (has_subtests(t))
@@ -307,29 +315,48 @@ static int finish_test(struct child_test *child_test, int width)
 			  .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
 			},
 		};
-		char buf[512];
-		ssize_t len;
-
-		/* Poll to avoid excessive spinning, timeout set for 100ms. */
-		poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
-		if (!err_done && pfds[0].revents) {
-			errno = 0;
-			len = read(err, buf, sizeof(buf) - 1);
-
-			if (len <= 0) {
-				err_done = errno != EAGAIN;
-			} else {
-				buf[len] = '\0';
-				if (verbose > 1)
-					fprintf(stdout, "%s", buf);
-				else
+		if (perf_use_color_default) {
+			int tests_in_progress = running_test;
+
+			for (int y = running_test; y < child_test_num; y++) {
+				if (check_if_command_finished(&child_tests[y]->process))
+					tests_in_progress++;
+			}
+			print_test_result(t, i, subi, TEST_RUNNING, width,
+					  child_test_num - tests_in_progress);
+		}
+
+		err_done = true;
+		if (err <= 0) {
+			/* No child stderr to poll, sleep for 10ms for child to complete. */
+			usleep(10 * 1000);
+		} else {
+			/* Poll to avoid excessive spinning, timeout set for 100ms. */
+			poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
+			if (pfds[0].revents) {
+				char buf[512];
+				ssize_t len;
+
+				len = read(err, buf, sizeof(buf) - 1);
+
+				if (len > 0) {
+					err_done = false;
+					buf[len] = '\0';
 					strbuf_addstr(&err_output, buf);
+				}
 			}
 		}
+		if (err_done)
+			err_done = check_if_command_finished(&child_test->process);
+
+		if (perf_use_color_default) {
+			/* Erase "Running (.. remaining)" line printed before poll/sleep. */
+			fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
+		}
 	}
 	/* Clean up child process. */
 	ret = finish_command(&child_test->process);
-	if (verbose == 1 && ret == TEST_FAIL) {
+	if (verbose > 1 || (verbose == 1 && ret == TEST_FAIL)) {
 		/* Add header for test that was skipped above. */
 		if (has_subtests(t))
 			pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
@@ -338,7 +365,7 @@ static int finish_test(struct child_test *child_test, int width)
 		fprintf(stderr, "%s", err_output.buf);
 	}
 	strbuf_release(&err_output);
-	print_test_result(t, i, subi, ret, width);
+	print_test_result(t, i, subi, ret, width, /*remaining=*/0);
 	if (err > 0)
 		close(err);
 	return 0;
@@ -354,7 +381,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
 		pr_debug("--- start ---\n");
 		err = test_function(test, subi)(test, subi);
 		pr_debug("---- end ----\n");
-		print_test_result(test, i, subi, err, width);
+		print_test_result(test, i, subi, err, width, /*remaining=*/0);
 		return 0;
 	}
 
@@ -379,7 +406,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
 	err = start_command(&(*child)->process);
 	if (err || !sequential)
 		return  err;
-	return finish_test(*child, width);
+	return finish_test(child, /*running_test=*/0, /*child_test_num=*/1, width);
 }
 
 #define for_each_test(j, k, t)					\
@@ -464,7 +491,7 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 	}
 	for (i = 0; i < child_test_num; i++) {
 		if (!sequential) {
-			int ret  = finish_test(child_tests[i], width);
+			int ret  = finish_test(child_tests, i, child_test_num, width);
 
 			if (ret)
 				return ret;
diff --git a/tools/perf/util/color.h b/tools/perf/util/color.h
index 01f7bed21c9b..4b9f8d5d4439 100644
--- a/tools/perf/util/color.h
+++ b/tools/perf/util/color.h
@@ -22,6 +22,7 @@
 #define MIN_GREEN	0.5
 #define MIN_RED		5.0
 
+#define PERF_COLOR_DELETE_LINE	"\033[A\33[2K\r"
 /*
  * This variable stores the value of color.ui
  */
-- 
2.45.2.803.g4e1b14247a-goog

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Namhyung Kim]

Hi Ian,

On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> Using waitpid can cause stdout/stderr of the child process to be
> lost. Use Linux's /prod/<pid>/status file to determine if the process
> has reached the zombie state. Use the 'status' file rather than 'stat'
> to avoid issues around skipping the process name.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> index 4e3a557a2f37..ec06683e77a0 100644
> --- a/tools/lib/subcmd/run-command.c
> +++ b/tools/lib/subcmd/run-command.c
> @@ -2,6 +2,7 @@
>  #include <unistd.h>
>  #include <sys/types.h>
>  #include <sys/stat.h>
> +#include <ctype.h>
>  #include <fcntl.h>
>  #include <string.h>
>  #include <linux/string.h>
> @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
>  
>  int check_if_command_finished(struct child_process *cmd)
>  {
> +#ifdef __linux__

Is this really necessary?  I don't think we plan to support other OS..

Thanks,
Namhyung


> +	char filename[FILENAME_MAX + 12];
> +	char status_line[256];
> +	FILE *status_file;
> +
> +	/*
> +	 * Check by reading /proc/<pid>/status as calling waitpid causes
> +	 * stdout/stderr to be closed and data lost.
> +	 */
> +	sprintf(filename, "/proc/%d/status", cmd->pid);
> +	status_file = fopen(filename, "r");
> +	if (status_file == NULL) {
> +		/* Open failed assume finish_command was called. */
> +		return true;
> +	}
> +	while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> +		char *p;
> +
> +		if (strncmp(status_line, "State:", 6))
> +			continue;
> +
> +		fclose(status_file);
> +		p = status_line + 6;
> +		while (isspace(*p))
> +			p++;
> +		return *p == 'Z';
> +	}
> +	/* Read failed assume finish_command was called. */
> +	fclose(status_file);
> +	return true;
> +#else
>  	wait_or_whine(cmd, /*block=*/false);
>  	return cmd->finished;
> +#endif
>  }
>  
>  int finish_command(struct child_process *cmd)
> -- 
> 2.45.2.803.g4e1b14247a-goog
> 

Re: [PATCH v2 2/2] perf test: Display number of remaining tests

[Namhyung Kim]

On Sun, Jun 30, 2024 at 09:42:36PM -0700, Ian Rogers wrote:
> Before polling or sleeping to wait for a test to complete, print out
> ": Running (<num> remaining)" where the number of remaining tests is
> determined by iterating over the remaining tests and seeing which
> return true for check_if_command_finished. After the delay, erase the
> line and either update it with the new number of remaining tests, or
> print the test's result. This allows a user to know a test is running
> and in parallel mode (default) how many of the tests are waiting to

It's not default anymore. :)


> complete. If color mode is disabled then avoid displaying the
> "Running" message.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/tests/builtin-test.c | 77 ++++++++++++++++++++++-----------
>  tools/perf/util/color.h         |  1 +
>  2 files changed, 53 insertions(+), 25 deletions(-)
> 
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index c3d84b67ca8e..23be9139f229 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -241,7 +241,10 @@ static int run_test_child(struct child_process *process)
>  	return -err;
>  }
>  
> -static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
> +#define TEST_RUNNING -3
> +
> +static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
> +			     int remaining)
>  {
>  	if (has_subtests(t)) {
>  		int subw = width > 2 ? width - 2 : width;
> @@ -251,6 +254,9 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
>  		pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
>  
>  	switch (result) {
> +	case TEST_RUNNING:
> +		color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d remaining)\n", remaining);
> +		break;
>  	case TEST_OK:
>  		pr_info(" Ok\n");
>  		break;
> @@ -272,13 +278,15 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
>  	return 0;
>  }
>  
> -static int finish_test(struct child_test *child_test, int width)
> +static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
> +		       int width)
>  {
> +	struct child_test *child_test = child_tests[running_test];
>  	struct test_suite *t = child_test->test;
>  	int i = child_test->test_num;
>  	int subi = child_test->subtest;
>  	int err = child_test->process.err;
> -	bool err_done = err <= 0;
> +	bool err_done = false;
>  	struct strbuf err_output = STRBUF_INIT;
>  	int ret;
>  
> @@ -293,7 +301,7 @@ static int finish_test(struct child_test *child_test, int width)
>  	 * Busy loop reading from the child's stdout/stderr that are set to be
>  	 * non-blocking until EOF.
>  	 */
> -	if (!err_done)
> +	if (err > 0)
>  		fcntl(err, F_SETFL, O_NONBLOCK);
>  	if (verbose > 1) {
>  		if (has_subtests(t))
> @@ -307,29 +315,48 @@ static int finish_test(struct child_test *child_test, int width)
>  			  .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
>  			},
>  		};
> -		char buf[512];
> -		ssize_t len;
> -
> -		/* Poll to avoid excessive spinning, timeout set for 100ms. */
> -		poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
> -		if (!err_done && pfds[0].revents) {
> -			errno = 0;
> -			len = read(err, buf, sizeof(buf) - 1);
> -
> -			if (len <= 0) {
> -				err_done = errno != EAGAIN;
> -			} else {
> -				buf[len] = '\0';
> -				if (verbose > 1)
> -					fprintf(stdout, "%s", buf);
> -				else
> +		if (perf_use_color_default) {
> +			int tests_in_progress = running_test;
> +
> +			for (int y = running_test; y < child_test_num; y++) {
> +				if (check_if_command_finished(&child_tests[y]->process))
> +					tests_in_progress++;
> +			}
> +			print_test_result(t, i, subi, TEST_RUNNING, width,
> +					  child_test_num - tests_in_progress);
> +		}
> +
> +		err_done = true;
> +		if (err <= 0) {
> +			/* No child stderr to poll, sleep for 10ms for child to complete. */
> +			usleep(10 * 1000);
> +		} else {
> +			/* Poll to avoid excessive spinning, timeout set for 100ms. */
> +			poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);

When I tested this patch, I saw it refreshes too often in parallel mode.
Maybe 100ms is too short?  I don't know if it's from usleep (10ms) or
here.

Thanks,
Namhyung


> +			if (pfds[0].revents) {
> +				char buf[512];
> +				ssize_t len;
> +
> +				len = read(err, buf, sizeof(buf) - 1);
> +
> +				if (len > 0) {
> +					err_done = false;
> +					buf[len] = '\0';
>  					strbuf_addstr(&err_output, buf);
> +				}
>  			}
>  		}
> +		if (err_done)
> +			err_done = check_if_command_finished(&child_test->process);
> +
> +		if (perf_use_color_default) {
> +			/* Erase "Running (.. remaining)" line printed before poll/sleep. */
> +			fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
> +		}
>  	}
>  	/* Clean up child process. */
>  	ret = finish_command(&child_test->process);
> -	if (verbose == 1 && ret == TEST_FAIL) {
> +	if (verbose > 1 || (verbose == 1 && ret == TEST_FAIL)) {
>  		/* Add header for test that was skipped above. */
>  		if (has_subtests(t))
>  			pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
> @@ -338,7 +365,7 @@ static int finish_test(struct child_test *child_test, int width)
>  		fprintf(stderr, "%s", err_output.buf);
>  	}
>  	strbuf_release(&err_output);
> -	print_test_result(t, i, subi, ret, width);
> +	print_test_result(t, i, subi, ret, width, /*remaining=*/0);
>  	if (err > 0)
>  		close(err);
>  	return 0;
> @@ -354,7 +381,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
>  		pr_debug("--- start ---\n");
>  		err = test_function(test, subi)(test, subi);
>  		pr_debug("---- end ----\n");
> -		print_test_result(test, i, subi, err, width);
> +		print_test_result(test, i, subi, err, width, /*remaining=*/0);
>  		return 0;
>  	}
>  
> @@ -379,7 +406,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
>  	err = start_command(&(*child)->process);
>  	if (err || !sequential)
>  		return  err;
> -	return finish_test(*child, width);
> +	return finish_test(child, /*running_test=*/0, /*child_test_num=*/1, width);
>  }
>  
>  #define for_each_test(j, k, t)					\
> @@ -464,7 +491,7 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
>  	}
>  	for (i = 0; i < child_test_num; i++) {
>  		if (!sequential) {
> -			int ret  = finish_test(child_tests[i], width);
> +			int ret  = finish_test(child_tests, i, child_test_num, width);
>  
>  			if (ret)
>  				return ret;
> diff --git a/tools/perf/util/color.h b/tools/perf/util/color.h
> index 01f7bed21c9b..4b9f8d5d4439 100644
> --- a/tools/perf/util/color.h
> +++ b/tools/perf/util/color.h
> @@ -22,6 +22,7 @@
>  #define MIN_GREEN	0.5
>  #define MIN_RED		5.0
>  
> +#define PERF_COLOR_DELETE_LINE	"\033[A\33[2K\r"
>  /*
>   * This variable stores the value of color.ui
>   */
> -- 
> 2.45.2.803.g4e1b14247a-goog
> 

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Ian Rogers]

On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> > Using waitpid can cause stdout/stderr of the child process to be
> > lost. Use Linux's /prod/<pid>/status file to determine if the process
> > has reached the zombie state. Use the 'status' file rather than 'stat'
> > to avoid issues around skipping the process name.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> >
> > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> > index 4e3a557a2f37..ec06683e77a0 100644
> > --- a/tools/lib/subcmd/run-command.c
> > +++ b/tools/lib/subcmd/run-command.c
> > @@ -2,6 +2,7 @@
> >  #include <unistd.h>
> >  #include <sys/types.h>
> >  #include <sys/stat.h>
> > +#include <ctype.h>
> >  #include <fcntl.h>
> >  #include <string.h>
> >  #include <linux/string.h>
> > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
> >
> >  int check_if_command_finished(struct child_process *cmd)
> >  {
> > +#ifdef __linux__
>
> Is this really necessary?  I don't think we plan to support other OS..

I don't think it'd be unreasonable to say run "perf report" on
Windows, or using wasm inside a web browser. Part of the reason for
doing things this way was to keep the WNOHANG logic although this
change no longer uses it for __linux__.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > +     char filename[FILENAME_MAX + 12];
> > +     char status_line[256];
> > +     FILE *status_file;
> > +
> > +     /*
> > +      * Check by reading /proc/<pid>/status as calling waitpid causes
> > +      * stdout/stderr to be closed and data lost.
> > +      */
> > +     sprintf(filename, "/proc/%d/status", cmd->pid);
> > +     status_file = fopen(filename, "r");
> > +     if (status_file == NULL) {
> > +             /* Open failed assume finish_command was called. */
> > +             return true;
> > +     }
> > +     while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> > +             char *p;
> > +
> > +             if (strncmp(status_line, "State:", 6))
> > +                     continue;
> > +
> > +             fclose(status_file);
> > +             p = status_line + 6;
> > +             while (isspace(*p))
> > +                     p++;
> > +             return *p == 'Z';
> > +     }
> > +     /* Read failed assume finish_command was called. */
> > +     fclose(status_file);
> > +     return true;
> > +#else
> >       wait_or_whine(cmd, /*block=*/false);
> >       return cmd->finished;
> > +#endif
> >  }
> >
> >  int finish_command(struct child_process *cmd)
> > --
> > 2.45.2.803.g4e1b14247a-goog
> >

Re: [PATCH v2 2/2] perf test: Display number of remaining tests

[Ian Rogers]

On Tue, Jul 2, 2024 at 8:40 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Sun, Jun 30, 2024 at 09:42:36PM -0700, Ian Rogers wrote:
> > Before polling or sleeping to wait for a test to complete, print out
> > ": Running (<num> remaining)" where the number of remaining tests is
> > determined by iterating over the remaining tests and seeing which
> > return true for check_if_command_finished. After the delay, erase the
> > line and either update it with the new number of remaining tests, or
> > print the test's result. This allows a user to know a test is running
> > and in parallel mode (default) how many of the tests are waiting to
>
> It's not default anymore. :)
>
>
> > complete. If color mode is disabled then avoid displaying the
> > "Running" message.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/tests/builtin-test.c | 77 ++++++++++++++++++++++-----------
> >  tools/perf/util/color.h         |  1 +
> >  2 files changed, 53 insertions(+), 25 deletions(-)
> >
> > diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> > index c3d84b67ca8e..23be9139f229 100644
> > --- a/tools/perf/tests/builtin-test.c
> > +++ b/tools/perf/tests/builtin-test.c
> > @@ -241,7 +241,10 @@ static int run_test_child(struct child_process *process)
> >       return -err;
> >  }
> >
> > -static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
> > +#define TEST_RUNNING -3
> > +
> > +static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
> > +                          int remaining)
> >  {
> >       if (has_subtests(t)) {
> >               int subw = width > 2 ? width - 2 : width;
> > @@ -251,6 +254,9 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
> >               pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
> >
> >       switch (result) {
> > +     case TEST_RUNNING:
> > +             color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d remaining)\n", remaining);
> > +             break;
> >       case TEST_OK:
> >               pr_info(" Ok\n");
> >               break;
> > @@ -272,13 +278,15 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
> >       return 0;
> >  }
> >
> > -static int finish_test(struct child_test *child_test, int width)
> > +static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
> > +                    int width)
> >  {
> > +     struct child_test *child_test = child_tests[running_test];
> >       struct test_suite *t = child_test->test;
> >       int i = child_test->test_num;
> >       int subi = child_test->subtest;
> >       int err = child_test->process.err;
> > -     bool err_done = err <= 0;
> > +     bool err_done = false;
> >       struct strbuf err_output = STRBUF_INIT;
> >       int ret;
> >
> > @@ -293,7 +301,7 @@ static int finish_test(struct child_test *child_test, int width)
> >        * Busy loop reading from the child's stdout/stderr that are set to be
> >        * non-blocking until EOF.
> >        */
> > -     if (!err_done)
> > +     if (err > 0)
> >               fcntl(err, F_SETFL, O_NONBLOCK);
> >       if (verbose > 1) {
> >               if (has_subtests(t))
> > @@ -307,29 +315,48 @@ static int finish_test(struct child_test *child_test, int width)
> >                         .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
> >                       },
> >               };
> > -             char buf[512];
> > -             ssize_t len;
> > -
> > -             /* Poll to avoid excessive spinning, timeout set for 100ms. */
> > -             poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
> > -             if (!err_done && pfds[0].revents) {
> > -                     errno = 0;
> > -                     len = read(err, buf, sizeof(buf) - 1);
> > -
> > -                     if (len <= 0) {
> > -                             err_done = errno != EAGAIN;
> > -                     } else {
> > -                             buf[len] = '\0';
> > -                             if (verbose > 1)
> > -                                     fprintf(stdout, "%s", buf);
> > -                             else
> > +             if (perf_use_color_default) {
> > +                     int tests_in_progress = running_test;
> > +
> > +                     for (int y = running_test; y < child_test_num; y++) {
> > +                             if (check_if_command_finished(&child_tests[y]->process))
> > +                                     tests_in_progress++;
> > +                     }
> > +                     print_test_result(t, i, subi, TEST_RUNNING, width,
> > +                                       child_test_num - tests_in_progress);
> > +             }
> > +
> > +             err_done = true;
> > +             if (err <= 0) {
> > +                     /* No child stderr to poll, sleep for 10ms for child to complete. */
> > +                     usleep(10 * 1000);
> > +             } else {
> > +                     /* Poll to avoid excessive spinning, timeout set for 100ms. */
> > +                     poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
>
> When I tested this patch, I saw it refreshes too often in parallel mode.
> Maybe 100ms is too short?  I don't know if it's from usleep (10ms) or
> here.

It's usually the poll and I suspect it is the test writing a lot of
output. I agree it can look a little flickery but it is also
responsive in terms of not waiting too long before moving to the next
test. I think it is possible to improve on the code here, the main
thing I was after was making the output writing self contained and not
split between start test and finish test, as that won't work well in
the parallel case.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > +                     if (pfds[0].revents) {
> > +                             char buf[512];
> > +                             ssize_t len;
> > +
> > +                             len = read(err, buf, sizeof(buf) - 1);
> > +
> > +                             if (len > 0) {
> > +                                     err_done = false;
> > +                                     buf[len] = '\0';
> >                                       strbuf_addstr(&err_output, buf);
> > +                             }
> >                       }
> >               }
> > +             if (err_done)
> > +                     err_done = check_if_command_finished(&child_test->process);
> > +
> > +             if (perf_use_color_default) {
> > +                     /* Erase "Running (.. remaining)" line printed before poll/sleep. */
> > +                     fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
> > +             }
> >       }
> >       /* Clean up child process. */
> >       ret = finish_command(&child_test->process);
> > -     if (verbose == 1 && ret == TEST_FAIL) {
> > +     if (verbose > 1 || (verbose == 1 && ret == TEST_FAIL)) {
> >               /* Add header for test that was skipped above. */
> >               if (has_subtests(t))
> >                       pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
> > @@ -338,7 +365,7 @@ static int finish_test(struct child_test *child_test, int width)
> >               fprintf(stderr, "%s", err_output.buf);
> >       }
> >       strbuf_release(&err_output);
> > -     print_test_result(t, i, subi, ret, width);
> > +     print_test_result(t, i, subi, ret, width, /*remaining=*/0);
> >       if (err > 0)
> >               close(err);
> >       return 0;
> > @@ -354,7 +381,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
> >               pr_debug("--- start ---\n");
> >               err = test_function(test, subi)(test, subi);
> >               pr_debug("---- end ----\n");
> > -             print_test_result(test, i, subi, err, width);
> > +             print_test_result(test, i, subi, err, width, /*remaining=*/0);
> >               return 0;
> >       }
> >
> > @@ -379,7 +406,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
> >       err = start_command(&(*child)->process);
> >       if (err || !sequential)
> >               return  err;
> > -     return finish_test(*child, width);
> > +     return finish_test(child, /*running_test=*/0, /*child_test_num=*/1, width);
> >  }
> >
> >  #define for_each_test(j, k, t)                                       \
> > @@ -464,7 +491,7 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
> >       }
> >       for (i = 0; i < child_test_num; i++) {
> >               if (!sequential) {
> > -                     int ret  = finish_test(child_tests[i], width);
> > +                     int ret  = finish_test(child_tests, i, child_test_num, width);
> >
> >                       if (ret)
> >                               return ret;
> > diff --git a/tools/perf/util/color.h b/tools/perf/util/color.h
> > index 01f7bed21c9b..4b9f8d5d4439 100644
> > --- a/tools/perf/util/color.h
> > +++ b/tools/perf/util/color.h
> > @@ -22,6 +22,7 @@
> >  #define MIN_GREEN    0.5
> >  #define MIN_RED              5.0
> >
> > +#define PERF_COLOR_DELETE_LINE       "\033[A\33[2K\r"
> >  /*
> >   * This variable stores the value of color.ui
> >   */
> > --
> > 2.45.2.803.g4e1b14247a-goog
> >

Re: [PATCH v2 2/2] perf test: Display number of remaining tests

[Namhyung Kim]

On Tue, Jul 02, 2024 at 09:30:44PM -0700, Ian Rogers wrote:
> On Tue, Jul 2, 2024 at 8:40 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > On Sun, Jun 30, 2024 at 09:42:36PM -0700, Ian Rogers wrote:
> > > Before polling or sleeping to wait for a test to complete, print out
> > > ": Running (<num> remaining)" where the number of remaining tests is
> > > determined by iterating over the remaining tests and seeing which
> > > return true for check_if_command_finished. After the delay, erase the
> > > line and either update it with the new number of remaining tests, or
> > > print the test's result. This allows a user to know a test is running
> > > and in parallel mode (default) how many of the tests are waiting to
> >
> > It's not default anymore. :)
> >
> >
> > > complete. If color mode is disabled then avoid displaying the
> > > "Running" message.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/tests/builtin-test.c | 77 ++++++++++++++++++++++-----------
> > >  tools/perf/util/color.h         |  1 +
> > >  2 files changed, 53 insertions(+), 25 deletions(-)
> > >
> > > diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> > > index c3d84b67ca8e..23be9139f229 100644
> > > --- a/tools/perf/tests/builtin-test.c
> > > +++ b/tools/perf/tests/builtin-test.c
> > > @@ -241,7 +241,10 @@ static int run_test_child(struct child_process *process)
> > >       return -err;
> > >  }
> > >
> > > -static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
> > > +#define TEST_RUNNING -3
> > > +
> > > +static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
> > > +                          int remaining)
> > >  {
> > >       if (has_subtests(t)) {
> > >               int subw = width > 2 ? width - 2 : width;
> > > @@ -251,6 +254,9 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
> > >               pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
> > >
> > >       switch (result) {
> > > +     case TEST_RUNNING:
> > > +             color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d remaining)\n", remaining);
> > > +             break;
> > >       case TEST_OK:
> > >               pr_info(" Ok\n");
> > >               break;
> > > @@ -272,13 +278,15 @@ static int print_test_result(struct test_suite *t, int i, int subtest, int resul
> > >       return 0;
> > >  }
> > >
> > > -static int finish_test(struct child_test *child_test, int width)
> > > +static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
> > > +                    int width)
> > >  {
> > > +     struct child_test *child_test = child_tests[running_test];
> > >       struct test_suite *t = child_test->test;
> > >       int i = child_test->test_num;
> > >       int subi = child_test->subtest;
> > >       int err = child_test->process.err;
> > > -     bool err_done = err <= 0;
> > > +     bool err_done = false;
> > >       struct strbuf err_output = STRBUF_INIT;
> > >       int ret;
> > >
> > > @@ -293,7 +301,7 @@ static int finish_test(struct child_test *child_test, int width)
> > >        * Busy loop reading from the child's stdout/stderr that are set to be
> > >        * non-blocking until EOF.
> > >        */
> > > -     if (!err_done)
> > > +     if (err > 0)
> > >               fcntl(err, F_SETFL, O_NONBLOCK);
> > >       if (verbose > 1) {
> > >               if (has_subtests(t))
> > > @@ -307,29 +315,48 @@ static int finish_test(struct child_test *child_test, int width)
> > >                         .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
> > >                       },
> > >               };
> > > -             char buf[512];
> > > -             ssize_t len;
> > > -
> > > -             /* Poll to avoid excessive spinning, timeout set for 100ms. */
> > > -             poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
> > > -             if (!err_done && pfds[0].revents) {
> > > -                     errno = 0;
> > > -                     len = read(err, buf, sizeof(buf) - 1);
> > > -
> > > -                     if (len <= 0) {
> > > -                             err_done = errno != EAGAIN;
> > > -                     } else {
> > > -                             buf[len] = '\0';
> > > -                             if (verbose > 1)
> > > -                                     fprintf(stdout, "%s", buf);
> > > -                             else
> > > +             if (perf_use_color_default) {
> > > +                     int tests_in_progress = running_test;
> > > +
> > > +                     for (int y = running_test; y < child_test_num; y++) {
> > > +                             if (check_if_command_finished(&child_tests[y]->process))
> > > +                                     tests_in_progress++;
> > > +                     }
> > > +                     print_test_result(t, i, subi, TEST_RUNNING, width,
> > > +                                       child_test_num - tests_in_progress);
> > > +             }
> > > +
> > > +             err_done = true;
> > > +             if (err <= 0) {
> > > +                     /* No child stderr to poll, sleep for 10ms for child to complete. */
> > > +                     usleep(10 * 1000);
> > > +             } else {
> > > +                     /* Poll to avoid excessive spinning, timeout set for 100ms. */
> > > +                     poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
> >
> > When I tested this patch, I saw it refreshes too often in parallel mode.
> > Maybe 100ms is too short?  I don't know if it's from usleep (10ms) or
> > here.
> 
> It's usually the poll and I suspect it is the test writing a lot of
> output. I agree it can look a little flickery but it is also
> responsive in terms of not waiting too long before moving to the next
> test. I think it is possible to improve on the code here, the main
> thing I was after was making the output writing self contained and not
> split between start test and finish test, as that won't work well in
> the parallel case.

Is it possible to skip the rewriting if nothing is changed?

Thanks,
Namhyung

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Namhyung Kim]

Hi Ian,

On Tue, Jul 02, 2024 at 09:24:50PM -0700, Ian Rogers wrote:
> On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Ian,
> >
> > On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> > > Using waitpid can cause stdout/stderr of the child process to be
> > > lost. Use Linux's /prod/<pid>/status file to determine if the process
> > > has reached the zombie state. Use the 'status' file rather than 'stat'
> > > to avoid issues around skipping the process name.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> > >  1 file changed, 33 insertions(+)
> > >
> > > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> > > index 4e3a557a2f37..ec06683e77a0 100644
> > > --- a/tools/lib/subcmd/run-command.c
> > > +++ b/tools/lib/subcmd/run-command.c
> > > @@ -2,6 +2,7 @@
> > >  #include <unistd.h>
> > >  #include <sys/types.h>
> > >  #include <sys/stat.h>
> > > +#include <ctype.h>
> > >  #include <fcntl.h>
> > >  #include <string.h>
> > >  #include <linux/string.h>
> > > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
> > >
> > >  int check_if_command_finished(struct child_process *cmd)
> > >  {
> > > +#ifdef __linux__
> >
> > Is this really necessary?  I don't think we plan to support other OS..
> 
> I don't think it'd be unreasonable to say run "perf report" on
> Windows, or using wasm inside a web browser. Part of the reason for
> doing things this way was to keep the WNOHANG logic although this
> change no longer uses it for __linux__.

I'm not sure we are ready to run it on other platforms.  So I think
it's better simply remove it for now.

Thanks,
Namhyung


> > > +     char filename[FILENAME_MAX + 12];
> > > +     char status_line[256];
> > > +     FILE *status_file;
> > > +
> > > +     /*
> > > +      * Check by reading /proc/<pid>/status as calling waitpid causes
> > > +      * stdout/stderr to be closed and data lost.
> > > +      */
> > > +     sprintf(filename, "/proc/%d/status", cmd->pid);
> > > +     status_file = fopen(filename, "r");
> > > +     if (status_file == NULL) {
> > > +             /* Open failed assume finish_command was called. */
> > > +             return true;
> > > +     }
> > > +     while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> > > +             char *p;
> > > +
> > > +             if (strncmp(status_line, "State:", 6))
> > > +                     continue;
> > > +
> > > +             fclose(status_file);
> > > +             p = status_line + 6;
> > > +             while (isspace(*p))
> > > +                     p++;
> > > +             return *p == 'Z';
> > > +     }
> > > +     /* Read failed assume finish_command was called. */
> > > +     fclose(status_file);
> > > +     return true;
> > > +#else
> > >       wait_or_whine(cmd, /*block=*/false);
> > >       return cmd->finished;
> > > +#endif
> > >  }
> > >
> > >  int finish_command(struct child_process *cmd)
> > > --
> > > 2.45.2.803.g4e1b14247a-goog
> > >

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Ian Rogers]

On Fri, Jul 12, 2024 at 1:33 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Tue, Jul 02, 2024 at 09:24:50PM -0700, Ian Rogers wrote:
> > On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim <namhyung@kernel.org> wrote:
> > >
> > > Hi Ian,
> > >
> > > On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> > > > Using waitpid can cause stdout/stderr of the child process to be
> > > > lost. Use Linux's /prod/<pid>/status file to determine if the process
> > > > has reached the zombie state. Use the 'status' file rather than 'stat'
> > > > to avoid issues around skipping the process name.
> > > >
> > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > ---
> > > >  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> > > >  1 file changed, 33 insertions(+)
> > > >
> > > > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> > > > index 4e3a557a2f37..ec06683e77a0 100644
> > > > --- a/tools/lib/subcmd/run-command.c
> > > > +++ b/tools/lib/subcmd/run-command.c
> > > > @@ -2,6 +2,7 @@
> > > >  #include <unistd.h>
> > > >  #include <sys/types.h>
> > > >  #include <sys/stat.h>
> > > > +#include <ctype.h>
> > > >  #include <fcntl.h>
> > > >  #include <string.h>
> > > >  #include <linux/string.h>
> > > > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
> > > >
> > > >  int check_if_command_finished(struct child_process *cmd)
> > > >  {
> > > > +#ifdef __linux__
> > >
> > > Is this really necessary?  I don't think we plan to support other OS..
> >
> > I don't think it'd be unreasonable to say run "perf report" on
> > Windows, or using wasm inside a web browser. Part of the reason for
> > doing things this way was to keep the WNOHANG logic although this
> > change no longer uses it for __linux__.
>
> I'm not sure we are ready to run it on other platforms.  So I think
> it's better simply remove it for now.

So in the office hours there was some discussion with a potential new
contributor whose development platform is OS/X. It's fairly obvious
this code can't work on anything but Linux and using #error feels
annoying. The waitpid code is tested and has a known issue, but I
think it is better than just breaking anyone not on Linux.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > > > +     char filename[FILENAME_MAX + 12];
> > > > +     char status_line[256];
> > > > +     FILE *status_file;
> > > > +
> > > > +     /*
> > > > +      * Check by reading /proc/<pid>/status as calling waitpid causes
> > > > +      * stdout/stderr to be closed and data lost.
> > > > +      */
> > > > +     sprintf(filename, "/proc/%d/status", cmd->pid);
> > > > +     status_file = fopen(filename, "r");
> > > > +     if (status_file == NULL) {
> > > > +             /* Open failed assume finish_command was called. */
> > > > +             return true;
> > > > +     }
> > > > +     while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> > > > +             char *p;
> > > > +
> > > > +             if (strncmp(status_line, "State:", 6))
> > > > +                     continue;
> > > > +
> > > > +             fclose(status_file);
> > > > +             p = status_line + 6;
> > > > +             while (isspace(*p))
> > > > +                     p++;
> > > > +             return *p == 'Z';
> > > > +     }
> > > > +     /* Read failed assume finish_command was called. */
> > > > +     fclose(status_file);
> > > > +     return true;
> > > > +#else
> > > >       wait_or_whine(cmd, /*block=*/false);
> > > >       return cmd->finished;
> > > > +#endif
> > > >  }
> > > >
> > > >  int finish_command(struct child_process *cmd)
> > > > --
> > > > 2.45.2.803.g4e1b14247a-goog
> > > >

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Namhyung Kim]

On Fri, Jul 12, 2024 at 02:19:58PM -0700, Ian Rogers wrote:
> On Fri, Jul 12, 2024 at 1:33 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Ian,
> >
> > On Tue, Jul 02, 2024 at 09:24:50PM -0700, Ian Rogers wrote:
> > > On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim <namhyung@kernel.org> wrote:
> > > >
> > > > Hi Ian,
> > > >
> > > > On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> > > > > Using waitpid can cause stdout/stderr of the child process to be
> > > > > lost. Use Linux's /prod/<pid>/status file to determine if the process
> > > > > has reached the zombie state. Use the 'status' file rather than 'stat'
> > > > > to avoid issues around skipping the process name.
> > > > >
> > > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > > ---
> > > > >  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> > > > >  1 file changed, 33 insertions(+)
> > > > >
> > > > > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> > > > > index 4e3a557a2f37..ec06683e77a0 100644
> > > > > --- a/tools/lib/subcmd/run-command.c
> > > > > +++ b/tools/lib/subcmd/run-command.c
> > > > > @@ -2,6 +2,7 @@
> > > > >  #include <unistd.h>
> > > > >  #include <sys/types.h>
> > > > >  #include <sys/stat.h>
> > > > > +#include <ctype.h>
> > > > >  #include <fcntl.h>
> > > > >  #include <string.h>
> > > > >  #include <linux/string.h>
> > > > > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
> > > > >
> > > > >  int check_if_command_finished(struct child_process *cmd)
> > > > >  {
> > > > > +#ifdef __linux__
> > > >
> > > > Is this really necessary?  I don't think we plan to support other OS..
> > >
> > > I don't think it'd be unreasonable to say run "perf report" on
> > > Windows, or using wasm inside a web browser. Part of the reason for
> > > doing things this way was to keep the WNOHANG logic although this
> > > change no longer uses it for __linux__.
> >
> > I'm not sure we are ready to run it on other platforms.  So I think
> > it's better simply remove it for now.
> 
> So in the office hours there was some discussion with a potential new
> contributor whose development platform is OS/X. It's fairly obvious
> this code can't work on anything but Linux and using #error feels
> annoying. The waitpid code is tested and has a known issue, but I
> think it is better than just breaking anyone not on Linux.

I feel like it's a potential issue and should be handled by the
potentiall contributor.  Until that happens, we can assume Linux
and keep the code minimal.

Thanks,
Namhyung

> >
> > > > > +     char filename[FILENAME_MAX + 12];
> > > > > +     char status_line[256];
> > > > > +     FILE *status_file;
> > > > > +
> > > > > +     /*
> > > > > +      * Check by reading /proc/<pid>/status as calling waitpid causes
> > > > > +      * stdout/stderr to be closed and data lost.
> > > > > +      */
> > > > > +     sprintf(filename, "/proc/%d/status", cmd->pid);
> > > > > +     status_file = fopen(filename, "r");
> > > > > +     if (status_file == NULL) {
> > > > > +             /* Open failed assume finish_command was called. */
> > > > > +             return true;
> > > > > +     }
> > > > > +     while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> > > > > +             char *p;
> > > > > +
> > > > > +             if (strncmp(status_line, "State:", 6))
> > > > > +                     continue;
> > > > > +
> > > > > +             fclose(status_file);
> > > > > +             p = status_line + 6;
> > > > > +             while (isspace(*p))
> > > > > +                     p++;
> > > > > +             return *p == 'Z';
> > > > > +     }
> > > > > +     /* Read failed assume finish_command was called. */
> > > > > +     fclose(status_file);
> > > > > +     return true;
> > > > > +#else
> > > > >       wait_or_whine(cmd, /*block=*/false);
> > > > >       return cmd->finished;
> > > > > +#endif
> > > > >  }
> > > > >
> > > > >  int finish_command(struct child_process *cmd)
> > > > > --
> > > > > 2.45.2.803.g4e1b14247a-goog
> > > > >

Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished()

[Ian Rogers]

On Sat, Jul 13, 2024 at 8:00 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Fri, Jul 12, 2024 at 02:19:58PM -0700, Ian Rogers wrote:
> > On Fri, Jul 12, 2024 at 1:33 PM Namhyung Kim <namhyung@kernel.org> wrote:
> > >
> > > Hi Ian,
> > >
> > > On Tue, Jul 02, 2024 at 09:24:50PM -0700, Ian Rogers wrote:
> > > > On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim <namhyung@kernel.org> wrote:
> > > > >
> > > > > Hi Ian,
> > > > >
> > > > > On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote:
> > > > > > Using waitpid can cause stdout/stderr of the child process to be
> > > > > > lost. Use Linux's /prod/<pid>/status file to determine if the process
> > > > > > has reached the zombie state. Use the 'status' file rather than 'stat'
> > > > > > to avoid issues around skipping the process name.
> > > > > >
> > > > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > > > ---
> > > > > >  tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> > > > > >  1 file changed, 33 insertions(+)
> > > > > >
> > > > > > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> > > > > > index 4e3a557a2f37..ec06683e77a0 100644
> > > > > > --- a/tools/lib/subcmd/run-command.c
> > > > > > +++ b/tools/lib/subcmd/run-command.c
> > > > > > @@ -2,6 +2,7 @@
> > > > > >  #include <unistd.h>
> > > > > >  #include <sys/types.h>
> > > > > >  #include <sys/stat.h>
> > > > > > +#include <ctype.h>
> > > > > >  #include <fcntl.h>
> > > > > >  #include <string.h>
> > > > > >  #include <linux/string.h>
> > > > > > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
> > > > > >
> > > > > >  int check_if_command_finished(struct child_process *cmd)
> > > > > >  {
> > > > > > +#ifdef __linux__
> > > > >
> > > > > Is this really necessary?  I don't think we plan to support other OS..
> > > >
> > > > I don't think it'd be unreasonable to say run "perf report" on
> > > > Windows, or using wasm inside a web browser. Part of the reason for
> > > > doing things this way was to keep the WNOHANG logic although this
> > > > change no longer uses it for __linux__.
> > >
> > > I'm not sure we are ready to run it on other platforms.  So I think
> > > it's better simply remove it for now.
> >
> > So in the office hours there was some discussion with a potential new
> > contributor whose development platform is OS/X. It's fairly obvious
> > this code can't work on anything but Linux and using #error feels
> > annoying. The waitpid code is tested and has a known issue, but I
> > think it is better than just breaking anyone not on Linux.
>
> I feel like it's a potential issue and should be handled by the
> potentiall contributor.  Until that happens, we can assume Linux
> and keep the code minimal.

I'm not clear what the issue is. Arnaldo took the WNOHANG waitpid
contribution but I asked him to drop it due to losing stdout/stderr in
parallel mode due to the waitpid closing these file descriptors early
- we're not running in parallel mode by default any more. Reading
procfs to determine zombie state is clearly a Linux only thing, hence
the ifdef. I'm keen to keep to any extent possible the perf tool
running on non-Linux platforms, for example, gathering a data file on
a server or embedded system then wanting to do perf report on a
different machine which may not be running Linux. libsubcmd is used
throughout the tool and we have many subprocesses for pagers, objdump,
addr2line, etc. I don't agree with making such a core library Linux
only and there's no obligation for the maintainers to take these
patches. I disagree with a minimal patch.

Thanks,
Ian

> Thanks,
> Namhyung
>
> > >
> > > > > > +     char filename[FILENAME_MAX + 12];
> > > > > > +     char status_line[256];
> > > > > > +     FILE *status_file;
> > > > > > +
> > > > > > +     /*
> > > > > > +      * Check by reading /proc/<pid>/status as calling waitpid causes
> > > > > > +      * stdout/stderr to be closed and data lost.
> > > > > > +      */
> > > > > > +     sprintf(filename, "/proc/%d/status", cmd->pid);
> > > > > > +     status_file = fopen(filename, "r");
> > > > > > +     if (status_file == NULL) {
> > > > > > +             /* Open failed assume finish_command was called. */
> > > > > > +             return true;
> > > > > > +     }
> > > > > > +     while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> > > > > > +             char *p;
> > > > > > +
> > > > > > +             if (strncmp(status_line, "State:", 6))
> > > > > > +                     continue;
> > > > > > +
> > > > > > +             fclose(status_file);
> > > > > > +             p = status_line + 6;
> > > > > > +             while (isspace(*p))
> > > > > > +                     p++;
> > > > > > +             return *p == 'Z';
> > > > > > +     }
> > > > > > +     /* Read failed assume finish_command was called. */
> > > > > > +     fclose(status_file);
> > > > > > +     return true;
> > > > > > +#else
> > > > > >       wait_or_whine(cmd, /*block=*/false);
> > > > > >       return cmd->finished;
> > > > > > +#endif
> > > > > >  }
> > > > > >
> > > > > >  int finish_command(struct child_process *cmd)
> > > > > > --
> > > > > > 2.45.2.803.g4e1b14247a-goog
> > > > > >