[dpdk-dev] [PATCH] Implement memcmp using AVX/SSE instructio
Bruce Richardson
bruce.richardson at intel.com
Thu Apr 23 10:11:39 CEST 2015
On Thu, Apr 23, 2015 at 09:24:52AM +0200, Pawel Wodkowski wrote:
> On 2015-04-22 17:33, Ravi Kerur wrote:
> >+/**
> >+ * Compare bytes between two locations. The locations must not overlap.
> >+ *
> >+ * @note This is implemented as a macro, so it's address should not be taken
> >+ * and care is needed as parameter expressions may be evaluated multiple times.
> >+ *
> >+ * @param src_1
> >+ * Pointer to the first source of the data.
> >+ * @param src_2
> >+ * Pointer to the second source of the data.
> >+ * @param n
> >+ * Number of bytes to compare.
> >+ * @return
> >+ * true if equal otherwise false.
> >+ */
> >+static inline bool
> >+rte_memcmp(const void *src_1, const void *src,
> >+ size_t n) __attribute__((always_inline));
> You are exposing this as public API, so I think you should follow
> description bellow or not call this _memcmp_
>
> int memcmp(const void *s1, const void *s2, size_t n);
>
> The memcmp() function returns an integer less than, equal to, or greater
> than
> zero if the first n bytes of s1 is found, respectively, to be
> less than, to
> match, or be greater than the first n bytes of s2.
>
+1 to this point.
Also, if I read your quoted performance numbers in your earlier mail correctly,
we are only looking at a 1-4% performance increase. Is the additional code to
maintain worth the benefit?
/Bruce
> --
> Pawel
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