From: Edward Cree <ecree@solarflare.com>
To: David Miller <davem@davemloft.net>
Cc: Tom Herbert <tom@herbertland.com>, netdev <netdev@vger.kernel.org>
Subject: [PATCH net-next 0/2] Local checksum offload for VXLAN
Date: Thu, 17 Dec 2015 15:27:34 +0000 [thread overview]
Message-ID: <5672D466.6050900@solarflare.com> (raw)
When the inner packet checksum is offloaded, the outer UDP checksum is easy
to calculate as it doesn't depend on the payload (because the inner checksum
cancels out everything from the inner packet except the pseudo header).
Thus, transmit checksums for VXLAN (and in principle other encapsulations,
but I haven't enabled it for / tested with those) can be offloaded on any
device supporting NETIF_F_HW_CSUM. Only the innermost checksum has to be
offloaded, the rest are filled in by the stack.
Tested by hacking a driver to report NETIF_F_HW_CSUM, call skb_checksum_help
before transmitting a packet, and not actually offload anything to the hw.
In principle it should also be possible to apply this technique when the
inner packet has been checksummed by software, but only if skb->csum_start
and skb->csum_offset have been filled in to describe the inner checksum.
However in this case it is easier to use skb->csum and skb->csum_start, as
gso_make_checksum() already does - a similar but simpler technique. It's
not clear to me where else this should be done, so this is out of scope for
this patch series.
Edward Cree (2):
net: udp: local checksum offload for encapsulation
net: vxlan: enable local checksum offload on HW_CSUM devices
drivers/net/vxlan.c | 5 ++++-
net/ipv4/udp.c | 34 +++++++++++++++++++++++++++++-----
2 files changed, 33 insertions(+), 6 deletions(-)
--
2.4.3
next reply other threads:[~2015-12-17 15:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 15:27 Edward Cree [this message]
2015-12-17 15:29 ` [PATCH net-next 1/2] net: udp: local checksum offload for encapsulation Edward Cree
2015-12-17 15:30 ` [PATCH net-next 2/2] net: vxlan: enable local checksum offload on HW_CSUM devices Edward Cree
2015-12-17 18:06 ` [PATCH net-next 0/2] Local checksum offload for VXLAN Tom Herbert
2015-12-18 10:41 ` Edward Cree
2015-12-18 19:41 ` Tom Herbert
2016-01-06 19:23 ` Edward Cree
2015-12-26 4:41 ` David Miller
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