RE: [PATCH v13 1/7] eal: add static per-lcore memory allocation facility

["Morten Brørup" <mb@smartsharesystems.com>]

> +void *
> +rte_lcore_var_alloc(size_t size, size_t align)
> +{
> +	/* Having the per-lcore buffer size aligned on cache lines
> +	 * assures as well as having the base pointer aligned on cache
> +	 * size assures that aligned offsets also translate to alipgned
> +	 * pointers across all values.
> +	 */
> +	RTE_BUILD_BUG_ON(RTE_MAX_LCORE_VAR % RTE_CACHE_LINE_SIZE != 0);
> +	RTE_VERIFY(align <= RTE_CACHE_LINE_SIZE);
> +	RTE_VERIFY(size <= RTE_MAX_LCORE_VAR);
> +
> +	/* '0' means asking for worst-case alignment requirements */
> +	if (align == 0)
> +#ifdef RTE_TOOLCHAIN_MSVC
> +		/* MSVC <stddef.h> is missing the max_align_t typedef */
> +		align = alignof(double);
> +#else
> +		align = alignof(max_align_t);
> +#endif

Do we need worst-case alignment, or does automatic alignment suffice:

	/* '0' means asking for automatic alignment requirements */
	if (align == 0) {
#ifdef RTE_ARCH_64
		align = rte_align64pow2(size);
#else
		align = rte_align32pow2(size);
#endif
#ifdef RTE_TOOLCHAIN_MSVC
		/* MSVC <stddef.h> is missing the max_align_t typedef */
		align = RTE_MIN(align, alignof(double));
#else
		align = RTE_MIN(align, alignof(max_align_t));
#endif
	}

It will pack small-size lcore variables even tighter.