Re: [dpdk-dev] [PATCH] Implement memcmp using AVX/SSE instructio

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> Sent: Thursday, April 23, 2015 9:12 AM
> To: Wodkowski, PawelX
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] Implement memcmp using AVX/SSE instructio
> 
> 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?

Yep, same thought here, is it really worth it?
Konstantin

> 
> /Bruce
> 
> > --
> > Pawel