[dpdk-dev] [PATCH v6 01/18] mbuf: redefine packet_type in rte_mbuf

Olivier MATZ olivier.matz at 6wind.com
Mon Jun 1 10:14:48 CEST 2015


Hi Helin,

+CC Neil

On 06/01/2015 09:33 AM, Helin Zhang wrote:
> In order to unify the packet type, the field of 'packet_type' in
> 'struct rte_mbuf' needs to be extended from 16 to 32 bits.
> Accordingly, some fields in 'struct rte_mbuf' are re-organized to
> support this change for Vector PMD. As 'struct rte_kni_mbuf' for
> KNI should be right mapped to 'struct rte_mbuf', it should be
> modified accordingly. In addition, Vector PMD of ixgbe is disabled
> by default, as 'struct rte_mbuf' changed.
> To avoid breaking ABI compatibility, all the changes would be
> enabled by RTE_UNIFIED_PKT_TYPE, which is disabled by default.

What are the plans for this compile-time option in the future?

I wonder what are the benefits of having this option in terms
of ABI compatibility: when it is disabled, it is ABI-compatible but
the packet-type feature is not present, and when it is enabled we
have the feature but it breaks the compatibility.

In my opinion, the v5 is preferable: for this kind of features, I
don't see how the ABI can be preserved, and I think packet-type
won't be the only feature that will modify the mbuf structure. I think
the process described here should be applied:
http://dpdk.org/browse/dpdk/tree/doc/guides/rel_notes/abi.rst

(starting from "Some ABI changes may be too significant to reasonably
maintain multiple versions of").


Regards,
Olivier



> 
> Signed-off-by: Helin Zhang <helin.zhang at intel.com>
> Signed-off-by: Cunming Liang <cunming.liang at intel.com>
> ---
>  config/common_linuxapp                             |  2 +-
>  .../linuxapp/eal/include/exec-env/rte_kni_common.h |  6 ++++++
>  lib/librte_mbuf/rte_mbuf.h                         | 23 ++++++++++++++++++++++
>  3 files changed, 30 insertions(+), 1 deletion(-)
> 
> v2 changes:
> * Enlarged the packet_type field from 16 bits to 32 bits.
> * Redefined the packet type sub-fields.
> * Updated the 'struct rte_kni_mbuf' for KNI according to the mbuf changes.
> 
> v3 changes:
> * Put the mbuf layout changes into a single patch.
> * Disabled vector ixgbe PMD by default, as mbuf layout changed.
> 
> v5 changes:
> * Re-worded the commit logs.
> 
> v6 changes:
> * Disabled the code changes for unified packet type by default, to
>   avoid breaking ABI compatibility.
> 
> diff --git a/config/common_linuxapp b/config/common_linuxapp
> index 0078dc9..6b067c7 100644
> --- a/config/common_linuxapp
> +++ b/config/common_linuxapp
> @@ -167,7 +167,7 @@ CONFIG_RTE_LIBRTE_IXGBE_DEBUG_TX_FREE=n
>  CONFIG_RTE_LIBRTE_IXGBE_DEBUG_DRIVER=n
>  CONFIG_RTE_LIBRTE_IXGBE_PF_DISABLE_STRIP_CRC=n
>  CONFIG_RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC=y
> -CONFIG_RTE_IXGBE_INC_VECTOR=y
> +CONFIG_RTE_IXGBE_INC_VECTOR=n
>  CONFIG_RTE_IXGBE_RX_OLFLAGS_ENABLE=y
>  
>  #
> diff --git a/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
> index 1e55c2d..7a2abbb 100644
> --- a/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
> +++ b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
> @@ -117,9 +117,15 @@ struct rte_kni_mbuf {
>  	uint16_t data_off;      /**< Start address of data in segment buffer. */
>  	char pad1[4];
>  	uint64_t ol_flags;      /**< Offload features. */
> +#ifdef RTE_UNIFIED_PKT_TYPE
> +	char pad2[4];
> +	uint32_t pkt_len;       /**< Total pkt len: sum of all segment data_len. */
> +	uint16_t data_len;      /**< Amount of data in segment buffer. */
> +#else
>  	char pad2[2];
>  	uint16_t data_len;      /**< Amount of data in segment buffer. */
>  	uint32_t pkt_len;       /**< Total pkt len: sum of all segment data_len. */
> +#endif
>  
>  	/* fields on second cache line */
>  	char pad3[8] __attribute__((__aligned__(RTE_CACHE_LINE_SIZE)));
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index ab6de67..a8662c2 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -269,6 +269,28 @@ struct rte_mbuf {
>  	/* remaining bytes are set on RX when pulling packet from descriptor */
>  	MARKER rx_descriptor_fields1;
>  
> +#ifdef RTE_UNIFIED_PKT_TYPE
> +	/*
> +	 * The packet type, which is the combination of outer/inner L2, L3, L4
> +	 * and tunnel types.
> +	 */
> +	union {
> +		uint32_t packet_type; /**< L2/L3/L4 and tunnel information. */
> +		struct {
> +			uint32_t l2_type:4; /**< (Outer) L2 type. */
> +			uint32_t l3_type:4; /**< (Outer) L3 type. */
> +			uint32_t l4_type:4; /**< (Outer) L4 type. */
> +			uint32_t tun_type:4; /**< Tunnel type. */
> +			uint32_t inner_l2_type:4; /**< Inner L2 type. */
> +			uint32_t inner_l3_type:4; /**< Inner L3 type. */
> +			uint32_t inner_l4_type:4; /**< Inner L4 type. */
> +		};
> +	};
> +
> +	uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
> +	uint16_t data_len;        /**< Amount of data in segment buffer. */
> +	uint16_t vlan_tci;        /**< VLAN Tag Control Identifier (CPU order) */
> +#else
>  	/**
>  	 * The packet type, which is used to indicate ordinary packet and also
>  	 * tunneled packet format, i.e. each number is represented a type of
> @@ -280,6 +302,7 @@ struct rte_mbuf {
>  	uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
>  	uint16_t vlan_tci;        /**< VLAN Tag Control Identifier (CPU order) */
>  	uint16_t reserved;
> +#endif
>  	union {
>  		uint32_t rss;     /**< RSS hash result if RSS enabled */
>  		struct {
> 


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