Re: [PATCH v2] perf sched replay: Fix -r/--repeat command line option for infinity

Madadi Vineeth Reddy
2024-06-28T02:30:50Z

On 21/06/24 22:49, Madadi Vineeth Reddy wrote:
> Currently, the -r/--repeat option accepts values from 0 and complains
> for -1. The help section specifies:
> -r, --repeat <n> repeat the workload replay N times (-1: infinite)
>
> The -r -1 option raises an error because replay_repeat is defined as
> an unsigned int.
>
> In the current implementation, the workload is repeated n times when
> -r <n> is used, except when n is 0.
>
> When -r is set to 0, the workload is also repeated once. This happens
> because when -r=0, the run_one_test function is not called. (Note that
> mutex unlocking, which is essential for child threads spawned to emulate
> the workload, happens in run_one_test.) However, mutex unlocking is
> still performed in the destroy_tasks function. Thus, -r=0 results in the
> workload running once coincidentally.
>
> To clarify and maintain the existing logic for -r >= 1 (which runs the
> workload the specified number of times) and to fix the issue with infinite
> runs, make -r=0 perform an infinite run.
>
> Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
> Reviewed-by: James Clark <james.clark@arm.com>
>

Hi all,
Any suggestions/comments on this patch?

Thanks and Regards
Madadi Vineeth Reddy

> ---
> Changes in v2:
> - Kept the existing 'for' loop and added a condition for infinite
> looping. (James Clark)
> - This change also ensures that integer overflow doesn't occur when
> 'replay_repeat' is zero.
> - Add Reviewed-by tag from James Clark.
> - Rebase against perf-tools-next commit 788c5160526a ("perf vendor
> events: Add westmereex counter information")
> - Link to v1: https://lore.kernel.org/all/20240618112907.15131-1-vineethr@linux.ibm.com/
>
> tools/perf/Documentation/perf-sched.txt | 7 +++++++
> tools/perf/builtin-sched.c | 11 ++++++++---
> 2 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
> index a216d2991b19..f1be8f0b249e 100644
> --- a/tools/perf/Documentation/perf-sched.txt
> +++ b/tools/perf/Documentation/perf-sched.txt
> @@ -202,6 +202,13 @@ OPTIONS for 'perf sched timehist'
> --state::
> Show task state when it switched out.
>
> +OPTIONS for 'perf sched replay'
> +------------------------------
> +
> +-r::
> +--repeat <n>::
> + repeat the workload n times (0: infinite). Default is 10.
> +
> SEE ALSO
> --------
> linkperf:perf-record[1]
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 8cdf18139a7e..51b3dea404bc 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -3383,8 +3383,13 @@ static int perf_sched__replay(struct perf_sched *sched)
> sched->thread_funcs_exit = false;
> create_tasks(sched);
> printf("------------------------------------------------------------\n");
> - for (i = 0; i < sched->replay_repeat; i++)
> - run_one_test(sched);
> + if (sched->replay_repeat == 0) {
> + while (1)
> + run_one_test(sched);
> + } else {
> + for (i = 0; i < sched->replay_repeat; i++)
> + run_one_test(sched);
> + }
>
> sched->thread_funcs_exit = true;
> destroy_tasks(sched);
> @@ -3548,7 +3553,7 @@ int cmd_sched(int argc, const char **argv)
> };
> const struct option replay_options[] = {
> OPT_UINTEGER('r', "repeat", &sched.replay_repeat,
> - "repeat the workload replay N times (-1: infinite)"),
> + "repeat the workload replay N times (0: infinite)"),
> OPT_PARENT(sched_options)
> };
> const struct option map_options[] = {