linux-kernel - Re: [PATCH 09/12] perf test: Add 'brstack' test workload

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Message-ID: <86c42368-cbbb-2e13-ce7d-31865a12bb81@arm.com>
Date:   Wed, 16 Nov 2022 11:39:29 +0000
From:   James Clark <james.clark@....com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, Leo Yan <leo.yan@...aro.org>,
        German Gomez <german.gomez@....com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        Athira Jajeev <atrajeev@...ux.vnet.ibm.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Subject: Re: [PATCH 09/12] perf test: Add 'brstack' test workload



On 10/11/2022 18:19, Namhyung Kim wrote:
[...]
> +
> +#define BENCH_RUNS 999999
> +
> +static volatile int cnt;
> +
> +static void brstack_bar(void) {
> +}				/* return */
> +
> +static void brstack_foo(void) {
> +	brstack_bar();		/* call */
> +}				/* return */
> +
> +static void brstack_bench(void) {
> +	void (*brstack_foo_ind)(void) = brstack_foo;
> +
> +	if ((cnt++) % 3)	/* branch (cond) */
> +		brstack_foo();	/* call */
> +	brstack_bar();		/* call */
> +	brstack_foo_ind();	/* call (ind) */
> +}
> +
> +static int brstack(int argc, const char **argv)
> +{
> +	if (argc > 0)
> +		cnt = atoi(argv[0]);
> +
> +	while (1) {
> +		if ((cnt++) > BENCH_RUNS)
> +			break;

Hi Namhyung,

I'm reading this as you can specify the number of loops as an argument.

In that case should it be more like this?

        int num_loops = argc>0 ? atoi(argv[0]) : BENCH_RUNS;

	if ((cnt++) > num_loops)
		break;

> +		brstack_bench();/* call */
> +	}			/* branch (uncond) */
> +	return 0;
> +}
> +
> +DEFINE_WORKLOAD(brstack);