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

Flavio Leitner fbl at sysclose.org
Wed Mar 11 12:13:55 UTC 2020


On Wed, Mar 11, 2020 at 11:47:22AM +0100, Ilya Maximets wrote:
> 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?

Then we will have cases like this just to set another flag:
    dp_packet_ol_flags_set(b, dp_packet_ol_flags_get(b) | FLAG);

I suspect that the define you proposed is better or the original
one.
    

> 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),
>     ...
> };

Exactly, looks better that way.

Thanks,
-- 
fbl


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