From: "didier.pallard" <didier.pallard@6wind.com>
To: jijiang.liu@intel.com, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v4 3/3] mbuf:replace the inner_l2_len and the inner_l3_len fields
Date: Tue, 02 Dec 2014 15:53:29 +0100 [thread overview]
Message-ID: <547DD269.2080500@6wind.com> (raw)
In-Reply-To: <1417503172-18642-4-git-send-email-jijiang.liu@intel.com>
Hello,
On 12/02/2014 07:52 AM, Jijiang Liu wrote:
> Replace the inner_l2_len and the inner_l3_len field with the outer_l2_len and outer_l3_len field, and rework csum forward engine and i40e PMD due to these changes.
>
> Signed-off-by: Jijiang Liu <jijiang.liu@intel.com>
[...]
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -276,8 +276,8 @@ struct rte_mbuf {
> uint64_t tso_segsz:16; /**< TCP TSO segment size */
>
> /* fields for TX offloading of tunnels */
> - uint64_t inner_l3_len:9; /**< inner L3 (IP) Hdr Length. */
> - uint64_t inner_l2_len:7; /**< inner L2 (MAC) Hdr Length. */
> + uint64_t outer_l3_len:9; /**< Outer L3 (IP) Hdr Length. */
> + uint64_t outer_l2_len:7; /**< Outer L2 (MAC) Hdr Length. */
>
> /* uint64_t unused:8; */
> };
Sorry for entering lately this discussion, but i'm not convinced by the
choice of outer_lx_len rather than inner_lx_len for new fields.
I agree with Olivier that new flags should only be related to the use of
new fields, to maintain coherency with oldest implementations.
But from a stack point of view, i think it is better to have lx_len
fields that target the outer layers, and to name new fields inner_lx_len.
Let's discuss the two possibilities.
1) outer_lx_len fields are introduced.
In this case, the stack should have knowledge that it is processing
tunneled packets to use outer_lx_len rather than lx_len,
or stack should always use outer_lx_len packet and move those fields to
lx_len packets if no tunneling occurs...
I think it will induce extra processing that does not seem to be really
needed.
2) inner_lx_len fields are introduced.
In this case, the stack first uses lx_len fields. When packet should be
tunneled, lx_len fields are moved to inner_lx_len fields.
Then the stack can process the outer layer and still use the lx_len fields.
For example:
an eth/IP/TCP forged packet will look like this:
Ether/IP/UDP/xxx
m->flags = IP_CKSUM
m->l2_len = sizeof(ether)
m->l3_len = sizeof(ip)
m->l4_len = sizeof(udp)
m->inner_l2_len = 0
m->inner_l3_len = 0
When entering tunnel for example a VXLAN interface, lx_len will be moved
to inner_lx_len
Ether/IP/UDP/xxx
m->flags = INNER_IP_CKSUM
m->l2_len = 0
m->l3_len = 0
m->l4_len = 0
m->inner_l2_len = sizeof(ether)
m->inner_l3_len = sizeof(ip)
once complete encapsulation is processed by the stack, the packet will
look like
Ether/IP/UDP/VXLAN/Ether/IP/UDP/xxx
m->flags = IP_CKSUM | INNER_IP_CKSUM
m->l2_len = sizeof(ether)
m->l3_len = sizeof(ip)
m->l4_len = sizeof(udp)
m->inner_l2_len = sizeof(ether) + sizeof (vxlan)
m->inner_l3_len = sizeof(ip)
didier
next prev parent reply other threads:[~2014-12-02 14:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-02 6:52 [dpdk-dev] [PATCH v4 0/3] i40e VXLAN TX checksum rework Jijiang Liu
2014-12-02 6:52 ` [dpdk-dev] [PATCH v4 1/3] mbuf:redefine three TX ol_flags Jijiang Liu
2014-12-02 6:52 ` [dpdk-dev] [PATCH v4 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM Jijiang Liu
2014-12-02 6:52 ` [dpdk-dev] [PATCH v4 3/3] mbuf:replace the inner_l2_len and the inner_l3_len fields Jijiang Liu
2014-12-02 14:53 ` didier.pallard [this message]
2014-12-02 15:36 ` Ananyev, Konstantin
2014-12-03 8:57 ` Olivier MATZ
2014-12-03 11:11 ` Ananyev, Konstantin
2014-12-03 11:27 ` Olivier MATZ
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