Hi,
13/10/2017 11:01, Xiaoyun Li:
> This patch dynamically selects functions of memcpy at run-time based
> on CPU flags that current machine supports. This patch uses function
> pointers which are bind to the relative functions at constrctor time.
> In addition, AVX512 instructions set would be compiled only if users
> config it enabled and the compiler supports it.
>
> Signed-off-by: Xiaoyun Li <xiaoyun...@intel.com>
> ---
Keeping only the major changes of the patch for later discussions:
[...]
> static inline void *
> rte_memcpy(void *dst, const void *src, size_t n)
> {
> - if (!(((uintptr_t)dst | (uintptr_t)src) & ALIGNMENT_MASK))
> - return rte_memcpy_aligned(dst, src, n);
> + if (n <= RTE_X86_MEMCPY_THRESH)
> + return rte_memcpy_internal(dst, src, n);
> else
> - return rte_memcpy_generic(dst, src, n);
> + return (*rte_memcpy_ptr)(dst, src, n);
> }
[...]
> +static inline void *
> +rte_memcpy_internal(void *dst, const void *src, size_t n)
> +{
> + if (!(((uintptr_t)dst | (uintptr_t)src) & ALIGNMENT_MASK))
> + return rte_memcpy_aligned(dst, src, n);
> + else
> + return rte_memcpy_generic(dst, src, n);
> +}
The significant change of this patch is to call a function pointer
for packet size > 128 (RTE_X86_MEMCPY_THRESH).
Please could you provide some benchmark numbers?
>From a test done at Mellanox, there might be a performance degradation
of about 15% in testpmd txonly with AVX2.
Is there someone else seeing a performance degradation?
