The RSS Hash is the output of the Toepliz Hash function. It is used by
masking some number of low-order bits of this function to get the RSS Index
used. As such 32-bits is more than sufficient since it is essentially maps
to the number of processing cores. A 32-bit hash supports 4 billion cores,
well beyond today's largest systems.
I'd leave it as uint32_t for now.
On Mon, Aug 17, 2015 at 3:45 AM, Santosh Shukla <santosh.shu...@linaro.org>
wrote:
> On 17 August 2015 at 14:09, Zoltan Kiss <zoltan.k...@linaro.org> wrote:
> >
> >
> > On 17/08/15 07:24, Maxim Uvarov wrote:
> >>
> >> On 08/14/15 21:42, Zoltan Kiss wrote:
> >>>
> >>> This platform doesn't compute it, packet_init set it to 0, which
> happens
> >>> to be ODP_PACKET_RSS_INVALID.
> >>>
> >>> Signed-off-by: Zoltan Kiss <zoltan.k...@linaro.org>
> >>> ---
> >>> platform/linux-generic/include/odp/plat/packet_types.h | 2 ++
> >>> platform/linux-generic/include/odp_packet_internal.h | 1 +
> >>> platform/linux-generic/odp_packet.c | 14
> >>> ++++++++++++++
> >>> 3 files changed, 17 insertions(+)
> >>>
> >>> diff --git a/platform/linux-generic/include/odp/plat/packet_types.h
> >>> b/platform/linux-generic/include/odp/plat/packet_types.h
> >>> index 45cb801..afc72f4 100644
> >>> --- a/platform/linux-generic/include/odp/plat/packet_types.h
> >>> +++ b/platform/linux-generic/include/odp/plat/packet_types.h
> >>> @@ -36,6 +36,8 @@ typedef ODP_HANDLE_T(odp_packet_seg_t);
> >>> #define ODP_PACKET_SEG_INVALID _odp_cast_scalar(odp_packet_seg_t,
> >>> 0xffffffff)
> >>> +#define ODP_PACKET_RSS_INVALID _odp_cast_scalar(odp_packet_t, 0)
> >
> >
> > This define is incorrect, I think.
> >
> >>> +
> >>> /** Get printable format of odp_packet_t */
> >>> static inline uint64_t odp_packet_to_u64(odp_packet_t hdl)
> >>> {
> >>> diff --git a/platform/linux-generic/include/odp_packet_internal.h
> >>> b/platform/linux-generic/include/odp_packet_internal.h
> >>> index 8c41491..6e52713 100644
> >>> --- a/platform/linux-generic/include/odp_packet_internal.h
> >>> +++ b/platform/linux-generic/include/odp_packet_internal.h
> >>> @@ -136,6 +136,7 @@ typedef struct {
> >>> uint32_t tailroom;
> >>> odp_pktio_t input;
> >>> + uint32_t rss_hash; /**< RSS hash value*/
> >>
> >>
> >> is rss_hash always and everywhere 32 bit?
> >
> >
> > I don't think it's guaranteed anywhere. Maybe we should rather use an
> opaque
> > type? But then we would need to provide operator functions for all the
> > possible uses, that would be an overkill.
> >
>
> So far per my knowledge; Plenty of NIC's example e100/ixgbe/brcm etc
> provide 32bit word size. You could add opaque support, but make sure
> handle/method are inlined (less expensive); Because its per-pkt
> Otherwise overkill. I would prefer keeping it 32bit word size unless
> someone speaks / describe their experience on using rss_hash 64bit
> word size.
>
> >>
> >> Maxim.
> >>
> >>
> >>> odp_crypto_generic_op_result_t op_result; /**< Result for
> >>> crypto */
> >>> } odp_packet_hdr_t;
> >>> diff --git a/platform/linux-generic/odp_packet.c
> >>> b/platform/linux-generic/odp_packet.c
> >>> index 5581cc4..649071f 100644
> >>> --- a/platform/linux-generic/odp_packet.c
> >>> +++ b/platform/linux-generic/odp_packet.c
> >>> @@ -326,6 +326,20 @@ int odp_packet_l4_offset_set(odp_packet_t pkt,
> >>> uint32_t offset)
> >>> return 0;
> >>> }
> >>> +uint32_t odp_packet_rss_hash(odp_packet_t pkt)
> >>> +{
> >>> + odp_packet_hdr_t *pkt_hdr = odp_packet_hdr(pkt);
> >>> +
> >>> + return pkt_hdr->rss_hash;
> >>> +}
> >>> +
> >>> +void odp_packet_rss_hash_set(odp_packet_t pkt, uint32_t rss_hash)
> >>> +{
> >>> + odp_packet_hdr_t *pkt_hdr = odp_packet_hdr(pkt);
> >>> +
> >>> + pkt_hdr->rss_hash = rss_hash;
> >>> +}
> >>> +
> >>> int odp_packet_is_segmented(odp_packet_t pkt)
> >>> {
> >>> return odp_packet_hdr(pkt)->buf_hdr.segcount > 1;
> >>
> >>
> >> _______________________________________________
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> >
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