Re: [PATCH v3 5/5] perf record off-cpu: Add direct off-cpu test

[Ian Rogers]

On Fri, Jul 26, 2024 at 3:28 AM Howard Chu <howardchu95@xxxxxxxxx> wrote:
>
> Add a simple workload(offcpu.c) to create the scenario for direct
> off-cpu dumping.
>
> Signed-off-by: Howard Chu <howardchu95@xxxxxxxxx>
> Suggested-by: Ian Rogers <irogers@xxxxxxxxxx>

I tried with and without --off-cpu-thresh=1 but I only see 1
offcpu-time sample and no offcpu-time-direct.

Thanks,
Ian

> ---
>  tools/perf/tests/builtin-test.c         |  1 +
>  tools/perf/tests/shell/record_offcpu.sh | 29 +++++++++++++++++++++++++
>  tools/perf/tests/tests.h                |  1 +
>  tools/perf/tests/workloads/Build        |  1 +
>  tools/perf/tests/workloads/offcpu.c     | 16 ++++++++++++++
>  5 files changed, 48 insertions(+)
>  create mode 100644 tools/perf/tests/workloads/offcpu.c
>
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index c3d84b67ca8e..5062058ad17d 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -152,6 +152,7 @@ static struct test_workload *workloads[] = {
>         &workload__sqrtloop,
>         &workload__brstack,
>         &workload__datasym,
> +       &workload__offcpu,
>  };
>
>  static int num_subtests(const struct test_suite *t)
> diff --git a/tools/perf/tests/shell/record_offcpu.sh b/tools/perf/tests/shell/record_offcpu.sh
> index 67c925f3a15a..1ea0a44336e2 100755
> --- a/tools/perf/tests/shell/record_offcpu.sh
> +++ b/tools/perf/tests/shell/record_offcpu.sh
> @@ -6,6 +6,7 @@ set -e
>
>  err=0
>  perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
> +TEST_PROGRAM="perf test -w offcpu"
>
>  cleanup() {
>    rm -f ${perfdata}
> @@ -88,6 +89,30 @@ test_offcpu_child() {
>    echo "Child task off-cpu test [Success]"
>  }
>
> +test_offcpu_direct() {
> +  echo "Direct off-cpu test"
> +  # dump off-cpu samples for tasks blocked for more than 1999ms (1.9s)
> +  # -D for initial delay, which is necessary if we want to enable evlist
> +  if ! perf record -F 1 -D 999 --off-cpu --off-cpu-thresh 1999 -o ${perfdata} ${TEST_PROGRAM} 2> /dev/null
> +  then
> +    echo "Direct off-cpu test [Failed record]"
> +    err=1
> +    return
> +  fi
> +  if ! perf evlist -i ${perfdata} | grep -q "offcpu-time-direct"
> +  then
> +    echo "Direct off-cpu test [Failed no event]"
> +    err=1
> +    return
> +  fi
> +  if ! perf script -i ${perfdata} | grep -q -E ".*2[0-9]{9}[ ]*offcpu-time-direct" # 2 seconds (2,000,000,000)
> +  then
> +    echo "Direct off-cpu test [Failed missing output]"
> +    err=1
> +    return
> +  fi
> +  echo "Direct off-cpu test [Success]"
> +}
>
>  test_offcpu_priv
>
> @@ -99,5 +124,9 @@ if [ $err = 0 ]; then
>    test_offcpu_child
>  fi
>
> +if [ $err = 0 ]; then
> +  test_offcpu_direct
> +fi
> +
>  cleanup
>  exit $err
> diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
> index 3aa7701ee0e9..84ab15683269 100644
> --- a/tools/perf/tests/tests.h
> +++ b/tools/perf/tests/tests.h
> @@ -205,6 +205,7 @@ DECLARE_WORKLOAD(leafloop);
>  DECLARE_WORKLOAD(sqrtloop);
>  DECLARE_WORKLOAD(brstack);
>  DECLARE_WORKLOAD(datasym);
> +DECLARE_WORKLOAD(offcpu);
>
>  extern const char *dso_to_test;
>  extern const char *test_objdump_path;
> diff --git a/tools/perf/tests/workloads/Build b/tools/perf/tests/workloads/Build
> index 48bf0d3b0f3d..f37e9be8b142 100644
> --- a/tools/perf/tests/workloads/Build
> +++ b/tools/perf/tests/workloads/Build
> @@ -6,6 +6,7 @@ perf-test-y += leafloop.o
>  perf-test-y += sqrtloop.o
>  perf-test-y += brstack.o
>  perf-test-y += datasym.o
> +perf-test-y += offcpu.o
>
>  CFLAGS_sqrtloop.o         = -g -O0 -fno-inline -U_FORTIFY_SOURCE
>  CFLAGS_leafloop.o         = -g -O0 -fno-inline -fno-omit-frame-pointer -U_FORTIFY_SOURCE
> diff --git a/tools/perf/tests/workloads/offcpu.c b/tools/perf/tests/workloads/offcpu.c
> new file mode 100644
> index 000000000000..02be3d05b06d
> --- /dev/null
> +++ b/tools/perf/tests/workloads/offcpu.c
> @@ -0,0 +1,16 @@
> +#include <linux/compiler.h>
> +#include <unistd.h>
> +#include "../tests.h"
> +
> +static int offcpu(int argc __maybe_unused, const char **argv __maybe_unused)
> +{
> +       /* get pass initial delay */
> +       sleep(1);
> +
> +       /* what we want to collect as a direct sample */
> +       sleep(2);
> +
> +       return 0;
> +}
> +
> +DEFINE_WORKLOAD(offcpu);
> --
> 2.45.2
>