[ovs-dev] [PATCHv3 1/2] userspace: Enable TSO support for non-DPDK.

Ilya Maximets i.maximets at ovn.org
Wed Mar 11 10:47:22 UTC 2020


On 3/10/20 10:01 PM, Flavio Leitner wrote:
> 
> Hi William,
> 
> Any chance to get the function comments copied to the non-dpdk
> versions as well?
> 
> I wonder if we could define DP_PACKET_OL.* defines as it is
> proposed in this patch if DPDK is not enabled, or define them
> as DPDK defines. For example:
> 
> #ifdef DPDK
>     DP_PACKET_OL_TX_TCP_SEG = PKT_TX_TCP_SEG
> #else
>     DP_PACKET_OL_TX_TCP_SEG = 0x40
> #endif
> 
> Then
> struct dp_packet
> #ifdef DPDK_NETDEV
>     struct rte_mbuf mbuf;       /* DPDK mbuf */
> #define ol_flags mbuf.ol_flags
> #else
>     void *base_;                /* First byte of allocated space. */
>     uint16_t allocated_;        /* Number of bytes allocated. */
>     uint16_t data_ofs;          /* First byte actually in use. */
>     uint32_t size_;             /* Number of bytes in use. */
>     uint32_t ol_flags;          /* Offloading flags. */
> 
> 
> 
> Then we would have a single:
> static inline bool
> dp_packet_hwol_is_tso(const struct dp_packet *b)
> {
>     return !!(b->ol_flags & PKT_TX_TCP_SEG);
> }
> 
> I haven't tried, so don't know if I am missing something or if it
> will look ugly, but it would save us many function copies.


Interesting.  I generally like the idea except the ' #define ol_flags'
part.   We should define something that could not be used accidentally,
e.g.

#ifdef DPDK_NETDEV
#define DP_PACKET_OL_FLAGS_FIELD  mbuf.ol_flags
#else
#define DP_PACKET_OL_FLAGS_FIELD  ol_flags
#endif
...
    return !!(b->DP_PACKET_OL_FLAGS_FIELD & PKT_TX_TCP_SEG);


Or, better write the inline access function that should look much
more clean:

static inline uint32_t *
dp_packet_ol_flags_get(const struct dp_packet *b)
{
#ifdef DPDK_NETDEV
    return &b->mbuf.ol_flags;
#else
    return &b->ol_flags;
#endif
}
...
    return !!(*dp_packet_ol_flags_get(b) & PKT_TX_TCP_SEG);
...
    *dp_packet_ol_flags_get(b) |= PKT_TX_SCTP_CKSUM;
...


What do you think?



Defines of flags might be shortened this way:

#ifdef DPDK_NETDEV
#define DEF_OL_FLAG(NAME, DPDK_DEF, GENERIC_DEF) NAME = DPDK_DEF
#else
#define DEF_OL_FLAG(NAME, DPDK_DEF, GENERIC_DEF) NAME = GENERIC_DEF
#endif

enum dp_packet_offload_mask {
    ...
    /* Valid IP checksum in the packet. */
    DEF_OL_FLAG(DP_PACKET_OL_RX_IP_CKSUM_GOOD, PKT_RX_IP_CKSUM_GOOD, 0x20),
    /* TCP Segmentation Offload. */
    DEF_OL_FLAG(DP_PACKET_OL_TX_TCP_SEG,       PKT_TX_TCP_SEG,       0x40),
    ...
};

Best regards, Ilya Maximets.


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