Re: [dpdk-dev] [PATCH v2] eal/windows: ensure all enabled CPUs are counted

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2021-06-29 18:56 (UTC-0700), Narcisa Ana Maria Vasile:
> From: Narcisa Vasile <navasile@microsoft.com>
> 
> rte_cpuset_t describes a set of CPUs by using an array of masks
> named '_bits'. Each element in the '_bits' array represents
> a bit mask, with each bit corresponding to a CPU.
> The maximum number of CPUs is given by 'CPU_SETSIZE'.
> The number of bit masks is computed using '_NUM_SETS(CPU_SETSIZE)'.
> 
> count_cpu() should count the number of CPUs enabled in the set 's'.
> Currently, it iterates through the number of masks in the
> set 's', instead of iterating through all the bits in all the masks.
> For example, if '_NUM_SETS(CPU_SETSIZE)' returns 2,
> which means there are 2 bit masks: _bits[0] and _bits[1],
> count_cpu() would only check if CPUs '0' and '1' are enabled.
> The correct behavior is to iterate through all the CPUs in the set and
> count the ones that are enabled.
> 
> This patch fixes count_cpu() to ensure all the bits in all the masks
> are checked to compute the correct number of CPUs enabled in 's'.
> 
> Fixes: e8428a9d89f1 ("eal/windows: add some basic functions and macros")
> Cc: pallavi.kadam@intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Narcisa Vasile <navasile@microsoft.com>
> ---
> v2:
>   * Fix commit message.
> 
>  lib/eal/windows/include/sched.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/eal/windows/include/sched.h b/lib/eal/windows/include/sched.h
> index ff572b5dcb..bc31cc8465 100644
> --- a/lib/eal/windows/include/sched.h
> +++ b/lib/eal/windows/include/sched.h
> @@ -49,7 +49,7 @@ count_cpu(rte_cpuset_t *s)
>  	unsigned int _i;
>  	int count = 0;
>  
> -	for (_i = 0; _i < _NUM_SETS(CPU_SETSIZE); _i++)
> +	for (_i = 0; _i < CPU_SETSIZE; _i++)
>  		if (CPU_ISSET(_i, s) != 0LL)
>  			count++;
>  	return count;

Sorry, I lost track of this patch.
Great and thorough explanation, but I don't think it needs to be so long.
Suggestion:

	On Windows, -l/--lcores EAL option was unable to process CPU sets
	containing CPUs other than 0 and 1, because CPU_COUNT() macro
	only checked these CPUs in the set. Fix CPU_COUNT() by enumerating
	all possible CPU indices.

Whatever message is taken in the end,
Acked-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>