[PATCH v2] perf test workload: Add thread count argument to thloop

[PATCH v2] perf test workload: Add thread count argument to thloop

[Ian Rogers]

Allow the number of threads for the thloop workload to be increased
beyond the normal 2. Add error checking to the parsed time and thread
count values.

Signed-off-by: Ian Rogers <irogers@google.com>
---
v2: Perform the pthread_join unconditionally and ensure started
    threads terminate.
---
 tools/perf/tests/workloads/thloop.c | 45 ++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/workloads/thloop.c b/tools/perf/tests/workloads/thloop.c
index 457b29f91c3e..bd8168f883fb 100644
--- a/tools/perf/tests/workloads/thloop.c
+++ b/tools/perf/tests/workloads/thloop.c
@@ -31,21 +31,52 @@ static void *thfunc(void *arg)
 
 static int thloop(int argc, const char **argv)
 {
-	int sec = 1;
-	pthread_t th;
+	int nt = 2, sec = 1, err = 1;
+	pthread_t *thread_list = NULL;
 
 	if (argc > 0)
 		sec = atoi(argv[0]);
 
+	if (sec <= 0) {
+		fprintf(stderr, "Error: seconds (%d) must be >= 1\n", sec);
+		return 1;
+	}
+
+	if (argc > 1)
+		nt = atoi(argv[1]);
+
+	if (nt <= 0) {
+		fprintf(stderr, "Error: thread count (%d) must be >= 1\n", nt);
+		return 1;
+	}
+
 	signal(SIGINT, sighandler);
 	signal(SIGALRM, sighandler);
-	alarm(sec);
 
-	pthread_create(&th, NULL, thfunc, test_loop);
-	test_loop();
-	pthread_join(th, NULL);
+	thread_list = calloc(nt, sizeof(pthread_t));
+	if (thread_list == NULL) {
+		fprintf(stderr, "Error: malloc failed for %d threads\n", nt);
+		goto out;
+	}
+	for (int i = 1; i < nt; i++) {
+		int ret = pthread_create(&thread_list[i], NULL, thfunc, test_loop);
 
-	return 0;
+		if (ret) {
+			fprintf(stderr, "Error: failed to create thread %d\n", i);
+			done = 1; // Ensure started threads terminate.
+			goto out;
+		}
+	}
+	alarm(sec);
+	test_loop();
+	err = 0;
+out:
+	for (int i = 1; i < nt; i++) {
+		if (thread_list && thread_list[i])
+			pthread_join(thread_list[i], /*retval=*/NULL);
+	}
+	free(thread_list);
+	return err;
 }
 
 DEFINE_WORKLOAD(thloop);
-- 
2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v2] perf test workload: Add thread count argument to thloop

[Arnaldo Carvalho de Melo]

On Tue, Oct 28, 2025 at 08:38:20AM -0700, Ian Rogers wrote:
> Allow the number of threads for the thloop workload to be increased
> beyond the normal 2. Add error checking to the parsed time and thread
> count values.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> v2: Perform the pthread_join unconditionally and ensure started
>     threads terminate.
> ---
>  tools/perf/tests/workloads/thloop.c | 45 ++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/tests/workloads/thloop.c b/tools/perf/tests/workloads/thloop.c
> index 457b29f91c3e..bd8168f883fb 100644
> --- a/tools/perf/tests/workloads/thloop.c
> +++ b/tools/perf/tests/workloads/thloop.c
> @@ -31,21 +31,52 @@ static void *thfunc(void *arg)
>  
>  static int thloop(int argc, const char **argv)
>  {
> -	int sec = 1;
> -	pthread_t th;
> +	int nt = 2, sec = 1, err = 1;
> +	pthread_t *thread_list = NULL;
>  
>  	if (argc > 0)
>  		sec = atoi(argv[0]);
>  
> +	if (sec <= 0) {
> +		fprintf(stderr, "Error: seconds (%d) must be >= 1\n", sec);
> +		return 1;
> +	}
> +
> +	if (argc > 1)
> +		nt = atoi(argv[1]);
> +
> +	if (nt <= 0) {
> +		fprintf(stderr, "Error: thread count (%d) must be >= 1\n", nt);
> +		return 1;
> +	}
> +
>  	signal(SIGINT, sighandler);
>  	signal(SIGALRM, sighandler);
> -	alarm(sec);
>  
> -	pthread_create(&th, NULL, thfunc, test_loop);
> -	test_loop();
> -	pthread_join(th, NULL);
> +	thread_list = calloc(nt, sizeof(pthread_t));
> +	if (thread_list == NULL) {
> +		fprintf(stderr, "Error: malloc failed for %d threads\n", nt);
> +		goto out;
> +	}
> +	for (int i = 1; i < nt; i++) {

Why do you start at 1? What goes in thread[0]? calloc() leaves it at
NULL, then if you have two threads you'll allocate thread[1], i gets
incremented, 2 < 2 fails, you get just one thread created, when two were
asked?

Oh, I see, you use the main thread to run, that test_loop() just before
the err = 0, its just that you allocate thread[0] for nothing, that
confused me.

- Arnaldo

> +		int ret = pthread_create(&thread_list[i], NULL, thfunc, test_loop);
>  
> -	return 0;
> +		if (ret) {
> +			fprintf(stderr, "Error: failed to create thread %d\n", i);
> +			done = 1; // Ensure started threads terminate.
> +			goto out;
> +		}
> +	}
> +	alarm(sec);
> +	test_loop();
> +	err = 0;
> +out:
> +	for (int i = 1; i < nt; i++) {
> +		if (thread_list && thread_list[i])
> +			pthread_join(thread_list[i], /*retval=*/NULL);
> +	}
> +	free(thread_list);
> +	return err;
>  }
>  
>  DEFINE_WORKLOAD(thloop);
> -- 
> 2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v2] perf test workload: Add thread count argument to thloop

[Ian Rogers]

On Tue, Oct 28, 2025 at 12:13 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> On Tue, Oct 28, 2025 at 08:38:20AM -0700, Ian Rogers wrote:
> > Allow the number of threads for the thloop workload to be increased
> > beyond the normal 2. Add error checking to the parsed time and thread
> > count values.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > v2: Perform the pthread_join unconditionally and ensure started
> >     threads terminate.
> > ---
> >  tools/perf/tests/workloads/thloop.c | 45 ++++++++++++++++++++++++-----
> >  1 file changed, 38 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/perf/tests/workloads/thloop.c b/tools/perf/tests/workloads/thloop.c
> > index 457b29f91c3e..bd8168f883fb 100644
> > --- a/tools/perf/tests/workloads/thloop.c
> > +++ b/tools/perf/tests/workloads/thloop.c
> > @@ -31,21 +31,52 @@ static void *thfunc(void *arg)
> >
> >  static int thloop(int argc, const char **argv)
> >  {
> > -     int sec = 1;
> > -     pthread_t th;
> > +     int nt = 2, sec = 1, err = 1;
> > +     pthread_t *thread_list = NULL;
> >
> >       if (argc > 0)
> >               sec = atoi(argv[0]);
> >
> > +     if (sec <= 0) {
> > +             fprintf(stderr, "Error: seconds (%d) must be >= 1\n", sec);
> > +             return 1;
> > +     }
> > +
> > +     if (argc > 1)
> > +             nt = atoi(argv[1]);
> > +
> > +     if (nt <= 0) {
> > +             fprintf(stderr, "Error: thread count (%d) must be >= 1\n", nt);
> > +             return 1;
> > +     }
> > +
> >       signal(SIGINT, sighandler);
> >       signal(SIGALRM, sighandler);
> > -     alarm(sec);
> >
> > -     pthread_create(&th, NULL, thfunc, test_loop);
> > -     test_loop();
> > -     pthread_join(th, NULL);
> > +     thread_list = calloc(nt, sizeof(pthread_t));
> > +     if (thread_list == NULL) {
> > +             fprintf(stderr, "Error: malloc failed for %d threads\n", nt);
> > +             goto out;
> > +     }
> > +     for (int i = 1; i < nt; i++) {
>
> Why do you start at 1? What goes in thread[0]? calloc() leaves it at
> NULL, then if you have two threads you'll allocate thread[1], i gets
> incremented, 2 < 2 fails, you get just one thread created, when two were
> asked?
>
> Oh, I see, you use the main thread to run, that test_loop() just before
> the err = 0, its just that you allocate thread[0] for nothing, that
> confused me.

Agreed. It was so I could avoid doing "nt-1" as I mentioned before.
Fwiw, pthread_self will sometimes return 0 for the main thread and so
it isn't entirely inconsistent to do things this way. Not that the
main thread should try to do a pthread_join with itself.

Thanks,
Ian

> - Arnaldo
>
> > +             int ret = pthread_create(&thread_list[i], NULL, thfunc, test_loop);
> >
> > -     return 0;
> > +             if (ret) {
> > +                     fprintf(stderr, "Error: failed to create thread %d\n", i);
> > +                     done = 1; // Ensure started threads terminate.
> > +                     goto out;
> > +             }
> > +     }
> > +     alarm(sec);
> > +     test_loop();
> > +     err = 0;
> > +out:
> > +     for (int i = 1; i < nt; i++) {
> > +             if (thread_list && thread_list[i])
> > +                     pthread_join(thread_list[i], /*retval=*/NULL);
> > +     }
> > +     free(thread_list);
> > +     return err;
> >  }
> >
> >  DEFINE_WORKLOAD(thloop);
> > --
> > 2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v2] perf test workload: Add thread count argument to thloop

[Arnaldo Carvalho de Melo]

On Tue, Oct 28, 2025 at 12:55:56PM -0700, Ian Rogers wrote:
> On Tue, Oct 28, 2025 at 12:13 PM Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> >
> > On Tue, Oct 28, 2025 at 08:38:20AM -0700, Ian Rogers wrote:
> > > Allow the number of threads for the thloop workload to be increased
> > > beyond the normal 2. Add error checking to the parsed time and thread
> > > count values.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > > v2: Perform the pthread_join unconditionally and ensure started
> > >     threads terminate.
> > > ---
> > >  tools/perf/tests/workloads/thloop.c | 45 ++++++++++++++++++++++++-----
> > >  1 file changed, 38 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/tools/perf/tests/workloads/thloop.c b/tools/perf/tests/workloads/thloop.c
> > > index 457b29f91c3e..bd8168f883fb 100644
> > > --- a/tools/perf/tests/workloads/thloop.c
> > > +++ b/tools/perf/tests/workloads/thloop.c
> > > @@ -31,21 +31,52 @@ static void *thfunc(void *arg)
> > >
> > >  static int thloop(int argc, const char **argv)
> > >  {
> > > -     int sec = 1;
> > > -     pthread_t th;
> > > +     int nt = 2, sec = 1, err = 1;
> > > +     pthread_t *thread_list = NULL;
> > >
> > >       if (argc > 0)
> > >               sec = atoi(argv[0]);
> > >
> > > +     if (sec <= 0) {
> > > +             fprintf(stderr, "Error: seconds (%d) must be >= 1\n", sec);
> > > +             return 1;
> > > +     }
> > > +
> > > +     if (argc > 1)
> > > +             nt = atoi(argv[1]);
> > > +
> > > +     if (nt <= 0) {
> > > +             fprintf(stderr, "Error: thread count (%d) must be >= 1\n", nt);
> > > +             return 1;
> > > +     }
> > > +
> > >       signal(SIGINT, sighandler);
> > >       signal(SIGALRM, sighandler);
> > > -     alarm(sec);
> > >
> > > -     pthread_create(&th, NULL, thfunc, test_loop);
> > > -     test_loop();
> > > -     pthread_join(th, NULL);
> > > +     thread_list = calloc(nt, sizeof(pthread_t));
> > > +     if (thread_list == NULL) {
> > > +             fprintf(stderr, "Error: malloc failed for %d threads\n", nt);
> > > +             goto out;
> > > +     }
> > > +     for (int i = 1; i < nt; i++) {
> >
> > Why do you start at 1? What goes in thread[0]? calloc() leaves it at
> > NULL, then if you have two threads you'll allocate thread[1], i gets
> > incremented, 2 < 2 fails, you get just one thread created, when two were
> > asked?
> >
> > Oh, I see, you use the main thread to run, that test_loop() just before
> > the err = 0, its just that you allocate thread[0] for nothing, that
> > confused me.
> 
> Agreed. It was so I could avoid doing "nt-1" as I mentioned before.
> Fwiw, pthread_self will sometimes return 0 for the main thread and so
> it isn't entirely inconsistent to do things this way. Not that the
> main thread should try to do a pthread_join with itself.

:-)

Its just a test,

Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 
> Thanks,
> Ian
> 
> > - Arnaldo
> >
> > > +             int ret = pthread_create(&thread_list[i], NULL, thfunc, test_loop);
> > >
> > > -     return 0;
> > > +             if (ret) {
> > > +                     fprintf(stderr, "Error: failed to create thread %d\n", i);
> > > +                     done = 1; // Ensure started threads terminate.
> > > +                     goto out;
> > > +             }
> > > +     }
> > > +     alarm(sec);
> > > +     test_loop();
> > > +     err = 0;
> > > +out:
> > > +     for (int i = 1; i < nt; i++) {
> > > +             if (thread_list && thread_list[i])
> > > +                     pthread_join(thread_list[i], /*retval=*/NULL);
> > > +     }
> > > +     free(thread_list);
> > > +     return err;
> > >  }
> > >
> > >  DEFINE_WORKLOAD(thloop);
> > > --
> > > 2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v2] perf test workload: Add thread count argument to thloop

[Namhyung Kim]

On Tue, 28 Oct 2025 08:38:20 -0700, Ian Rogers wrote:
> Allow the number of threads for the thloop workload to be increased
> beyond the normal 2. Add error checking to the parsed time and thread
> count values.
> 
> 
Applied to perf-tools-next, thanks!

Best regards,
Namhyung