|author||David S. Miller <firstname.lastname@example.org>||2016-02-21 22:05:50 -0500|
|committer||David S. Miller <email@example.com>||2016-02-21 22:05:50 -0500|
Merge branch 'geneve-vxlan-outer-checksum'
Alexander Duyck says: ==================== GENEVE/VXLAN: Enable outer Tx checksum by default This patch series makes it so that we enable the outer Tx checksum for IPv4 tunnels by default. This makes the behavior consistent with how we were handling this for IPv6. In addition I have updated the internal flags for these tunnels so that we use a ZERO_CSUM_TX flag for IPv4 which should match up will with the ZERO_CSUM6_TX flag which was already in use for IPv6. For most network devices this should be a net gain in terms of performance as having the outer header checksum present allows for devices to report CHECKSUM_UNNECESSARY which we can then convert to CHECKSUM_COMPLETE in order to determine if the inner header checksum is valid. Below is some data I collected with ixgbe with an X540 that demonstrates this. I located two PFs connected back to back in two different name spaces and then setup a pair of tunnels on each, one with checksum enabled and one without. Recv Send Send Utilization Socket Socket Message Elapsed Send Size Size Size Time Throughput local bytes bytes bytes secs. 10^6bits/s % S noudpcsum: 87380 16384 16384 30.00 8898.67 12.80 udpcsum: 87380 16384 16384 30.00 9088.47 5.69 The one spot where this may cause a performance regression is if the environment contains devices that can parse the inner headers and a device supports NETIF_F_GSO_UDP_TUNNEL but not NETIF_F_GSO_UDP_TUNNEL_CSUM. In the case of such a device we have to fall back to using GSO to segment the tunnel instead of TSO and as a result we may take a performance hit as seen below with i40e. Recv Send Send Utilization Socket Socket Message Elapsed Send Size Size Size Time Throughput local bytes bytes bytes secs. 10^6bits/s % S noudpcsum: 87380 16384 16384 30.00 9085.21 3.32 udpcsum: 87380 16384 16384 30.00 9089.23 5.54 In addition it will be necessary to update iproute2 so that we don't provide the checksum attribute unless specified. This way on older kernels which don't have local checksum offload we will default to disabling the outer checksum, and on newer kernels that have LCO we can default to enabling it. I also haven't investigated the effect this will have on OVS. However I suspect the impact should be minimal as the worst case scenario should be that Tx checksumming will become enabled by default which should be consistent with the existing behavior for IPv6. ==================== Signed-off-by: David S. Miller <firstname.lastname@example.org>
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