linux-kernel - Re: [PATCH 1/3] tools/perf: Fix the nrcpus in perf bench futex to enable the run when all CPU's are not online

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Message-ID: <CAP-5=fVCXW1FEBra5aFLJm48f0-b4a+oTugTZt+VYEv1EySBKg@mail.gmail.com>
Date: Fri, 7 Jun 2024 10:23:11 -0700
From: Ian Rogers <irogers@...gle.com>
To: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc: acme@...nel.org, jolsa@...nel.org, adrian.hunter@...el.com, 
	namhyung@...nel.org, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	akanksha@...ux.ibm.com, maddy@...ux.ibm.com, kjain@...ux.ibm.com, 
	disgoel@...ux.vnet.ibm.com
Subject: Re: [PATCH 1/3] tools/perf: Fix the nrcpus in perf bench futex to
 enable the run when all CPU's are not online

On Thu, Jun 6, 2024 at 9:44 PM Athira Rajeev
<atrajeev@...ux.vnet.ibm.com> wrote:
>
> Perf bench futex fails as below when attempted to run on
> on a powerpc system:
>
>  ./perf bench futex all
>  Running futex/hash benchmark...
> Run summary [PID 626307]: 80 threads, each operating on 1024 [private] futexes for 10 secs.
>
> perf: pthread_create: No such file or directory
>
> In the setup where this perf bench was ran, difference was that
> partition had 640 CPU's, but not all CPUs were online. 80 CPUs
> were online. While blocking the threads with futex_wait, code
> sets the affinity using cpumask. The cpumask size used is 80
> which is picked from "nrcpus = perf_cpu_map__nr(cpu)". Here the
> benchmark reports fail while setting affinity for cpu number which
> is greater than 80 or higher, because it attempts to set a bit
> position which is not allocated on the cpumask. Fix this by changing
> the size of cpumask to number of possible cpus and not the number
> of online cpus.
>
> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>

For the series:
Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  tools/perf/bench/futex-hash.c          | 2 +-
>  tools/perf/bench/futex-lock-pi.c       | 2 +-
>  tools/perf/bench/futex-requeue.c       | 2 +-
>  tools/perf/bench/futex-wake-parallel.c | 2 +-
>  tools/perf/bench/futex-wake.c          | 2 +-
>  5 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c
> index 0c69d20efa32..b472eded521b 100644
> --- a/tools/perf/bench/futex-hash.c
> +++ b/tools/perf/bench/futex-hash.c
> @@ -174,7 +174,7 @@ int bench_futex_hash(int argc, const char **argv)
>         pthread_attr_init(&thread_attr);
>         gettimeofday(&bench__start, NULL);
>
> -       nrcpus = perf_cpu_map__nr(cpu);
> +       nrcpus = cpu__max_cpu().cpu;
>         cpuset = CPU_ALLOC(nrcpus);
>         BUG_ON(!cpuset);
>         size = CPU_ALLOC_SIZE(nrcpus);
> diff --git a/tools/perf/bench/futex-lock-pi.c b/tools/perf/bench/futex-lock-pi.c
> index 7a4973346180..0416120c091b 100644
> --- a/tools/perf/bench/futex-lock-pi.c
> +++ b/tools/perf/bench/futex-lock-pi.c
> @@ -122,7 +122,7 @@ static void create_threads(struct worker *w, struct perf_cpu_map *cpu)
>  {
>         cpu_set_t *cpuset;
>         unsigned int i;
> -       int nrcpus =  perf_cpu_map__nr(cpu);
> +       int nrcpus =  cpu__max_cpu().cpu;
>         size_t size;
>
>         threads_starting = params.nthreads;
> diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
> index d9ad736c1a3e..aad5bfc4fe18 100644
> --- a/tools/perf/bench/futex-requeue.c
> +++ b/tools/perf/bench/futex-requeue.c
> @@ -125,7 +125,7 @@ static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
>  {
>         cpu_set_t *cpuset;
>         unsigned int i;
> -       int nrcpus = perf_cpu_map__nr(cpu);
> +       int nrcpus = cpu__max_cpu().cpu;
>         size_t size;
>
>         threads_starting = params.nthreads;
> diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c
> index b66df553e561..90a5b91bf139 100644
> --- a/tools/perf/bench/futex-wake-parallel.c
> +++ b/tools/perf/bench/futex-wake-parallel.c
> @@ -149,7 +149,7 @@ static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
>  {
>         cpu_set_t *cpuset;
>         unsigned int i;
> -       int nrcpus = perf_cpu_map__nr(cpu);
> +       int nrcpus = cpu__max_cpu().cpu;
>         size_t size;
>
>         threads_starting = params.nthreads;
> diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c
> index 690fd6d3da13..49b3c89b0b35 100644
> --- a/tools/perf/bench/futex-wake.c
> +++ b/tools/perf/bench/futex-wake.c
> @@ -100,7 +100,7 @@ static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
>         cpu_set_t *cpuset;
>         unsigned int i;
>         size_t size;
> -       int nrcpus = perf_cpu_map__nr(cpu);
> +       int nrcpus = cpu__max_cpu().cpu;
>         threads_starting = params.nthreads;
>
>         cpuset = CPU_ALLOC(nrcpus);
> --
> 2.43.0
>