linux-kernel - Re: [PATCH v5 02/14] perf bench mem: Defer type munging of size to float

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Message-ID: <aHa0j7AtLgnd_53B@google.com>
Date: Tue, 15 Jul 2025 13:05:35 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
	akpm@...ux-foundation.org, david@...hat.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
	mjguzik@...il.com, luto@...nel.org, peterz@...radead.org,
	acme@...nel.org, tglx@...utronix.de, willy@...radead.org,
	raghavendra.kt@....com, boris.ostrovsky@...cle.com,
	konrad.wilk@...cle.com
Subject: Re: [PATCH v5 02/14] perf bench mem: Defer type munging of size to
 float

On Wed, Jul 09, 2025 at 05:59:14PM -0700, Ankur Arora wrote:
> Do type conversion to double at the point of use.
> 
> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>

Reviewed-by: Namhyung Kim <namhyung@...nel.org>

A nitpick below.

> ---
>  tools/perf/bench/mem-functions.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/bench/mem-functions.c b/tools/perf/bench/mem-functions.c
> index 8599ed96ee1f..b8f020379197 100644
> --- a/tools/perf/bench/mem-functions.c
> +++ b/tools/perf/bench/mem-functions.c
> @@ -139,7 +139,7 @@ struct bench_mem_info {
>  	bool alloc_src;
>  };
>  
> -static void __bench_mem_function(struct bench_mem_info *info, int r_idx, size_t size, double size_total)
> +static void __bench_mem_function(struct bench_mem_info *info, int r_idx, size_t size, size_t size_total)
>  {
>  	const struct function *r = &info->functions[r_idx];
>  	double result_bps = 0.0;
> @@ -165,18 +165,18 @@ static void __bench_mem_function(struct bench_mem_info *info, int r_idx, size_t
>  	switch (bench_format) {
>  	case BENCH_FORMAT_DEFAULT:
>  		if (use_cycles) {
> -			printf(" %14lf cycles/byte\n", (double)rt.cycles/size_total);
> +			printf(" %14lf cycles/byte\n", (double)rt.cycles/(double)size_total);
>  		} else {
> -			result_bps = size_total/timeval2double(&rt.tv);
> +			result_bps = (double)size_total/timeval2double(&rt.tv);
>  			print_bps(result_bps);
>  		}
>  		break;
>  
>  	case BENCH_FORMAT_SIMPLE:
>  		if (use_cycles) {
> -			printf("%lf\n", (double)rt.cycles/size_total);
> +			printf("%lf\n", (double)rt.cycles/(double)size_total);
>  		} else {
> -			result_bps = size_total/timeval2double(&rt.tv);
> +			result_bps = (double)size_total/timeval2double(&rt.tv);
>  			printf("%lf\n", result_bps);
>  		}
>  		break;
> @@ -199,7 +199,7 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
>  {
>  	int i;
>  	size_t size;
> -	double size_total;
> +	size_t size_total;
>  
>  	argc = parse_options(argc, argv, options, info->usage, 0);
>  
> @@ -212,7 +212,7 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
>  	}
>  
>  	size = (size_t)perf_atoll((char *)size_str);
> -	size_total = (double)size * nr_loops;
> +	size_total = (size_t)size * nr_loops;

No need to cast.

Thanks,
Namhyung

>  
>  	if ((s64)size <= 0) {
>  		fprintf(stderr, "Invalid size:%s\n", size_str);
> -- 
> 2.43.5
>