[PATCH] perf stat: Set child_pid after perf_evlist__prepare_workload()

[PATCH] perf stat: Set child_pid after perf_evlist__prepare_workload()

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

The commit acf2892270dc ("perf stat: Use perf_evlist__prepare/
start_workload()") converted to use the function but forgot to update
child_pid.  Fix it.

Cc: David Ahern <dsahern@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-stat.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index f686d5ff594e..5098f144b92d 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -457,6 +457,7 @@ static int __run_perf_stat(int argc, const char **argv)
 			perror("failed to prepare workload");
 			return -1;
 		}
+		child_pid = evsel_list->workload.pid;
 	}
 
 	if (group)
-- 
1.7.11.7

Re: [PATCH] perf stat: Set child_pid after perf_evlist__prepare_workload()

[David Ahern]

On 9/30/13 3:01 AM, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@lge.com>
>
> The commit acf2892270dc ("perf stat: Use perf_evlist__prepare/
> start_workload()") converted to use the function but forgot to update
> child_pid.  Fix it.
>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Stephane Eranian <eranian@google.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>   tools/perf/builtin-stat.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index f686d5ff594e..5098f144b92d 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -457,6 +457,7 @@ static int __run_perf_stat(int argc, const char **argv)
>   			perror("failed to prepare workload");
>   			return -1;
>   		}
> +		child_pid = evsel_list->workload.pid;
>   	}
>
>   	if (group)
>

Interesting. I can't find a test case where is matters ... perhaps a 
convenience of waitpid taking -1.

David

Re: [PATCH] perf stat: Set child_pid after perf_evlist__prepare_workload()

[Arnaldo Carvalho de Melo]

Em Mon, Sep 30, 2013 at 07:47:25AM -0600, David Ahern escreveu:
> On 9/30/13 3:01 AM, Namhyung Kim wrote:
> >From: Namhyung Kim <namhyung.kim@lge.com>
> >
> >The commit acf2892270dc ("perf stat: Use perf_evlist__prepare/
> >start_workload()") converted to use the function but forgot to update
> >child_pid.  Fix it.
> >
> >Cc: David Ahern <dsahern@gmail.com>
> >Cc: Stephane Eranian <eranian@google.com>
> >Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> >---
> >  tools/perf/builtin-stat.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> >diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> >index f686d5ff594e..5098f144b92d 100644
> >--- a/tools/perf/builtin-stat.c
> >+++ b/tools/perf/builtin-stat.c
> >@@ -457,6 +457,7 @@ static int __run_perf_stat(int argc, const char **argv)
> >  			perror("failed to prepare workload");
> >  			return -1;
> >  		}
> >+		child_pid = evsel_list->workload.pid;
> >  	}
> >
> >  	if (group)
> >
> 
> Interesting. I can't find a test case where is matters ... perhaps a
> convenience of waitpid taking -1.

Yeah, the interval part initially used the fork return, then after
acf2892270dc used the default value of child_pid, -1, which is ok as it
waits for any children, but I wonder what would happen in workloads with
multiple children.

But for correctness acf2892270dc should have kept the existing
semantics, even if using -1 could in the end be ok.

- Arnaldo

Re: [PATCH] perf stat: Set child_pid after perf_evlist__prepare_workload()

[Namhyung Kim]

On Tue, 1 Oct 2013 13:51:33 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Sep 30, 2013 at 07:47:25AM -0600, David Ahern escreveu:
>> On 9/30/13 3:01 AM, Namhyung Kim wrote:
>> >From: Namhyung Kim <namhyung.kim@lge.com>
>> >
>> >The commit acf2892270dc ("perf stat: Use perf_evlist__prepare/
>> >start_workload()") converted to use the function but forgot to update
>> >child_pid.  Fix it.
>> >
>> >Cc: David Ahern <dsahern@gmail.com>
>> >Cc: Stephane Eranian <eranian@google.com>
>> >Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>> >---
>> >  tools/perf/builtin-stat.c | 1 +
>> >  1 file changed, 1 insertion(+)
>> >
>> >diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>> >index f686d5ff594e..5098f144b92d 100644
>> >--- a/tools/perf/builtin-stat.c
>> >+++ b/tools/perf/builtin-stat.c
>> >@@ -457,6 +457,7 @@ static int __run_perf_stat(int argc, const char **argv)
>> >  			perror("failed to prepare workload");
>> >  			return -1;
>> >  		}
>> >+		child_pid = evsel_list->workload.pid;
>> >  	}
>> >
>> >  	if (group)
>> >
>> 
>> Interesting. I can't find a test case where is matters ... perhaps a
>> convenience of waitpid taking -1.
>
> Yeah, the interval part initially used the fork return, then after
> acf2892270dc used the default value of child_pid, -1, which is ok as it
> waits for any children, but I wonder what would happen in workloads with
> multiple children.

Hmm.. right.  And in fact what I actually concern was when killing child
if create_perf_stat_counter() failed.

	if (child_pid != -1)
		kill(child_pid, SIGTERM);

>
> But for correctness acf2892270dc should have kept the existing
> semantics, even if using -1 could in the end be ok.

Agreed.

Thanks,
Namhyung

[tip:perf/urgent] perf stat: Set child_pid after perf_evlist__prepare_workload()

[tip-bot for Namhyung Kim]

Commit-ID:  d20a47e70b57a77f4d1b0dba98a668e14c2f9bf9
Gitweb:     http://git.kernel.org/tip/d20a47e70b57a77f4d1b0dba98a668e14c2f9bf9
Author:     Namhyung Kim <namhyung.kim@lge.com>
AuthorDate: Mon, 30 Sep 2013 18:01:11 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 4 Oct 2013 15:16:05 -0300

perf stat: Set child_pid after perf_evlist__prepare_workload()

The commit acf2892270dc ("perf stat: Use perf_evlist__prepare/
start_workload()") converted to use the function but forgot to update
child_pid.  Fix it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1380531671-28076-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-stat.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index f686d5f..5098f14 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -457,6 +457,7 @@ static int __run_perf_stat(int argc, const char **argv)
 			perror("failed to prepare workload");
 			return -1;
 		}
+		child_pid = evsel_list->workload.pid;
 	}
 
 	if (group)