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Date:   Tue, 12 Dec 2023 11:25:14 +0000
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Subject: Re: [PATCH v1 13/14] perf cpumap: Use perf_cpu_map__for_each_cpu when
 possible
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To:     Ian Rogers <irogers@google.com>
References: <20231129060211.1890454-1-irogers@google.com>
 <20231129060211.1890454-14-irogers@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mike Leach <mike.leach@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        John Garry <john.g.garry@oracle.com>,
        Will Deacon <will@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Darren Hart <dvhart@infradead.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        =?UTF-8?Q?Andr=c3=a9_Almeida?= <andrealmeid@igalia.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Andrew Jones <ajones@ventanamicro.com>,
        Alexandre Ghiti <alexghiti@rivosinc.com>,
        Atish Patra <atishp@rivosinc.com>,
        "Steinar H. Gunderson" <sesse@google.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Yang Li <yang.lee@linux.alibaba.com>,
        Changbin Du <changbin.du@huawei.com>,
        Sandipan Das <sandipan.das@amd.com>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        Paran Lee <p4ranlee@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Yanteng Si <siyanteng@loongson.cn>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
        bpf@vger.kernel.org
From:   James Clark <james.clark@arm.com>
In-Reply-To: <20231129060211.1890454-14-irogers@google.com>
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On 29/11/2023 06:02, Ian Rogers wrote:
> Rather than manually iterating the CPU map, use
> perf_cpu_map__for_each_cpu. When possible tidy local variables.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/arch/arm64/util/header.c           | 10 ++--
>  tools/perf/tests/bitmap.c                     | 13 +++---
>  tools/perf/tests/topology.c                   | 46 +++++++++----------
>  tools/perf/util/bpf_kwork.c                   | 16 ++++---
>  tools/perf/util/bpf_kwork_top.c               | 12 ++---
>  tools/perf/util/cpumap.c                      | 12 ++---
>  .../scripting-engines/trace-event-python.c    | 12 +++--
>  tools/perf/util/session.c                     |  5 +-
>  tools/perf/util/svghelper.c                   | 20 ++++----
>  9 files changed, 72 insertions(+), 74 deletions(-)
> 
[...]
> diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
> index 860e1837ba96..8ef0e5ac03c2 100644
> --- a/tools/perf/util/scripting-engines/trace-event-python.c
> +++ b/tools/perf/util/scripting-engines/trace-event-python.c
> @@ -1693,13 +1693,15 @@ static void python_process_stat(struct perf_stat_config *config,
>  {
>  	struct perf_thread_map *threads = counter->core.threads;
>  	struct perf_cpu_map *cpus = counter->core.cpus;
> -	int cpu, thread;
>  
> -	for (thread = 0; thread < perf_thread_map__nr(threads); thread++) {
> -		for (cpu = 0; cpu < perf_cpu_map__nr(cpus); cpu++) {
> -			process_stat(counter, perf_cpu_map__cpu(cpus, cpu),
> +	for (int thread = 0; thread < perf_thread_map__nr(threads); thread++) {
> +		int idx;
> +		struct perf_cpu cpu;
> +
> +		perf_cpu_map__for_each_cpu(cpu, idx, cpus) {
> +			process_stat(counter, cpu,
>  				     perf_thread_map__pid(threads, thread), tstamp,
> -				     perf_counts(counter->counts, cpu, thread));
> +				     perf_counts(counter->counts, idx, thread));

I thought changing cpu to idx was fixing a bug, but it was actually just
hard to read before where cpu was actually idx and not cpu, so this
cleanup is pretty good.

Reviewed-by: James Clark <james.clark@arm.com>