Re: [PATCH] latencystats: fix missing f suffix on literal float

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 15 Apr 2024 14:32:26 -0700
Tyler Retzlaff <roretzla@linux.microsoft.com> wrote:

> Add missing f suffix to floating point literal to avoid warning about
> truncation from double to float.
> 
> Fixes: 5cd3cac9ed22 ("latency: added new library for latency stats")
> Cc: reshma.pattan@intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> ---
>  lib/latencystats/rte_latencystats.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/latencystats/rte_latencystats.c b/lib/latencystats/rte_latencystats.c
> index 4ea9b0d..cae4b50 100644
> --- a/lib/latencystats/rte_latencystats.c
> +++ b/lib/latencystats/rte_latencystats.c
> @@ -166,7 +166,7 @@ struct latency_stats_nameoff {
>  	 * a constant smoothing factor between 0 and 1. The value
>  	 * is used below for measuring average latency.
>  	 */
> -	const float alpha = 0.2;
> +	const float alpha = 0.2f;
>  
>  	now = rte_rdtsc();
>  	for (i = 0; i < nb_pkts; i++) {

The use of floating point in fast path here is unnecessary.
Even without doing the full per-core values, this could just change
to an alpha of .25 and use fast fixed point math.