Re: [dpdk-dev] [PATCH] mbuf: extend rte_mbuf_prefetch_part* to support more prefetching methods

[Jianbo Liu <jianbo.liu@linaro.org>]

On 2 June 2016 at 15:10, Olivier MATZ <olivier.matz@6wind.com> wrote:
> Hi Jianbo,
>
> On 06/01/2016 05:29 AM, Jianbo Liu wrote:
>>> enum rte_mbuf_prefetch_type {
>>> >         PREFETCH0,
>>> >         PREFETCH1,
>>> > ...
>>> > };
>>> >
>>> > static inline void
>>> > rte_mbuf_prefetch_part1(enum rte_mbuf_prefetch_type type,
>>> >         struct rte_mbuf *m)
>>> > {
>>> >         switch (type) {
>>> >         case PREFETCH0:
>>> >                 rte_prefetch0(&m->cacheline0);
>>> >                 break;
>>> >         case PREFETCH1:
>>> >                 rte_prefetch1(&m->cacheline0);
>>> >                 break;
>>> >         ...
>>> > }
>>> >
>> How about adding these to forbid the illegal use of this macro?
>> enum rte_mbuf_prefetch_type {
>>          ENUM_prefetch0,
>>          ENUM_prefetch1,
>>  ...
>> };
>>
>> #define RTE_MBUF_PREFETCH_PART1(type, m) \
>>     if (ENUM_##type == ENUM_prefretch0) \
>>         rte_prefetch0(&(m)->cacheline0);   \
>>     else if (ENUM_##type == ENUM_prefetch1) \
>>         rte_prefetch1(&(m)->cacheline0); \
>>     ....
>>
>
> As Stephen stated, a static inline is better than a macro, mainly
> because it is understood by the compiler instead of beeing a dumb
> code replacement.
>
> Any reason why you would prefer a macro in that case?
>
For the simplicity reason. If not, we may have to write several
similar functions for different prefetchings.