Re: [dpdk-dev] [PATCH v5] Add toeplitz hash algorithm used by RSS

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Jun 30, 2015 at 03:14:55PM +0300, Vladimir Medvedkin wrote:
> Hi Bruce,
> 
> 2015-06-29 15:40 GMT+03:00 Bruce Richardson <bruce.richardson@intel.com>:
> 
> > On Fri, Jun 19, 2015 at 01:31:13PM -0400, Vladimir Medvedkin wrote:
> > > Software implementation of the Toeplitz hash function used by RSS.
> > > Can be used either for packet distribution on single queue NIC
> > > or for simulating of RSS computation on specific NIC (for example
> > > after GRE header decapsulating).
> > >
> > > v5 changes
> > > - Fix errors reported by checkpatch.pl
> > >
> > > v4 changes
> > > - Fix copyright
> > > - rename bswap_mask constant, add rte_ prefix
> > > - change rte_ipv[46]_tuple struct
> > > - change rte_thash_load_v6_addr prototype
> > >
> > > v3 changes
> > > - Rework API to be more generic
> > > - Add sctp_tag into tuple
> > >
> > > v2 changes
> > > - Add ipv6 support
> > > - Various style fixes
> > >
> > > Signed-off-by: Vladimir Medvedkin <medvedkinv@gmail.com>
> > > ---
> > >  lib/librte_hash/Makefile    |   1 +
> > >  lib/librte_hash/rte_thash.h | 207
> > ++++++++++++++++++++++++++++++++++++++++++++
> > >  2 files changed, 208 insertions(+)
> > >  create mode 100644 lib/librte_hash/rte_thash.h
> > >
> > <snip>
> > > +static const __m128i rte_thash_ipv6_bswap_mask = {
> > > +             0x0405060700010203, 0x0C0D0E0F08090A0B};
> > > +
> > > +#define RTE_THASH_V4_L3       2      /*calculate hash of ipv4 header
> > only*/
> > > +#define RTE_THASH_V4_L4       3      /*calculate hash of ipv4 +
> > transport headers*/
> > > +#define RTE_THASH_V6_L3       8      /*calculate hash of ipv6 header
> > only */
> > > +#define RTE_THASH_V6_L4       9      /*calculate hash of ipv6 +
> > transport headers */
> > > +
> >
> > Comment as on V4 patch - add LEN to name to make it clear they are lengths
> > in quadwords.
> >
> Agree, but length dwords
> 
Yes, my mistake.

> >
> > > +/**
> > > + * IPv4 tuple
> > > + * addreses and ports/sctp_tag have to be CPU byte order
> > > + */
> > > +struct rte_ipv4_tuple {
> > > +     uint32_t        src_addr;
> > > +     uint32_t        dst_addr;
> > > +     union {
> > > +             struct {
> > > +                     uint16_t dport;
> > > +                     uint16_t sport;
> > > +             };
> > > +             uint32_t        sctp_tag;
> > > +     };
> > > +};
> > > +
> > > +/**
> > > + * IPv6 tuple
> > > + * Addresses have to be filled by rte_thash_load_v6_addr()
> > > + * ports/sctp_tag have to be CPU byte order
> > > + */
> > > +struct rte_ipv6_tuple {
> > > +     uint8_t         src_addr[16];
> > > +     uint8_t         dst_addr[16];
> > > +     union {
> > > +             struct {
> > > +                     uint16_t dport;
> > > +                     uint16_t sport;
> > > +             };
> > > +             uint32_t        sctp_tag;
> > > +     };
> > > +};
> > > +
> > > +union rte_thash_tuple {
> > > +     struct rte_ipv4_tuple   v4;
> > > +     struct rte_ipv6_tuple   v6;
> > > +} __aligned(size);
> > > +
> > This throws an error on compilation [with unit test patch also applied].
> >
> I will never copy paste
> I will never copy paste
> I will never... =)
> 
> >
> > In file included from /home/bruce/dpdk.org/app/test/test_thash.c:40:0:
> > /home/bruce/dpdk.org/x86_64-native-linuxapp-gcc/include/rte_thash.h:106:1:
> > error: parameter names (without types) in function declaration [-Werror]
> >  } __aligned(size);
> >   ^
> >
> > +/**
> > > + * Prepare special converted key to use with rte_softrss_be()
> > > + * @param orig
> > > + *   pointer to original RSS key
> > > + * @param targ
> > > + *   pointer to target RSS key
> > > + * @param len
> > > + *   RSS key length
> > > + */
> > > +static inline void
> > > +rte_convert_rss_key(const uint32_t *orig, uint32_t *targ, int len)
> > > +{
> > > +     int i;
> > > +
> > > +     for (i = 0; i < (len >> 2); i++)
> > > +             targ[i] = rte_be_to_cpu_32(orig[i]);
> > > +}
> > > +
> > > +/**
> > > + * Prepare and load IPv6 address
> > > + * @param orig
> > > + *   Pointer to ipv6 header of the original packet
> > > + * @param targ
> > > + *   Pointer to rte_ipv6_tuple structure
> > > + */
> > > +static inline void
> > > +rte_thash_load_v6_addr(const struct ipv6_hdr *orig, union
> > rte_thash_tuple *targ)
> > > +{
> > > +     __m128i ipv6 = _mm_loadu_si128((const __m128i *)orig->src_addr);
> > > +     *(__m128i *)targ->v6.src_addr =
> > > +                     _mm_shuffle_epi8(ipv6, rte_thash_ipv6_bswap_mask);
> > > +     ipv6 = _mm_loadu_si128((const __m128i *)orig->dst_addr);
> > > +     *(__m128i *)targ->v6.dst_addr =
> > > +                     _mm_shuffle_epi8(ipv6, rte_thash_ipv6_bswap_mask);
> > > +}
> >
> > I think the function name needs to be pluralized, and the comment updated
> > to make
> > it clear that it is not just one IPv6 address that is loaded, but rather
> > both
> > source and destination.
> >
> I think no need to make too long function name like
> rte_thash_load_v6_addresses(), instead I'll make comment more clear.
> Is it enough?

I was actually thinking "addrs" rather than full "addresses" in the name. The extra
"s" should be enough to make it appear as plural. Please make the comment clear 
anyway.

/Bruce