When using TSO in OVS-DPDK with an i40e device, the following patch is required for DPDK, which fixes an issue on the TSO path: https://patches.dpdk.org/patch/64136/ Document this as a limitation until a DPDK release with the fix included is supported by OVS.
Also, document best known methods for performance tuning when testing TSO with the tool iperf. Signed-off-by: Ciara Loftus <ciara.lof...@intel.com> Acked-by: Flavio Leitner <f...@sysclose.org> --- v2: - rebased to master - changed patch links from net-next tree to patchwork --- Documentation/topics/userspace-tso.rst | 27 ++++++++++++++++++++++++++ manpages.mk | 3 --- 2 files changed, 27 insertions(+), 3 deletions(-) diff --git a/Documentation/topics/userspace-tso.rst b/Documentation/topics/userspace-tso.rst index 893c64839..94eddc0b2 100644 --- a/Documentation/topics/userspace-tso.rst +++ b/Documentation/topics/userspace-tso.rst @@ -96,3 +96,30 @@ datapath must support TSO or packets using that feature will be dropped on ports without TSO support. That also means guests using vhost-user in client mode will receive TSO packet regardless of TSO being enabled or disabled within the guest. + +When the NIC performing the segmentation is using the i40e DPDK PMD, a fix +must be included in the DPDK build, otherwise TSO will not work. The fix can +be found on `DPDK patchwork`__. + +__ https://patches.dpdk.org/patch/64136/ + +This fix is expected to be included in the 19.11.1 release. When OVS migrates +to this DPDK release, this limitation can be removed. + +~~~~~~~~~~~~~~~~~~ +Performance Tuning +~~~~~~~~~~~~~~~~~~ + +iperf is often used to test TSO performance. Care needs to be taken when +configuring the environment in which the iperf server process is being run. +Since the iperf server uses the NIC's kernel driver, IRQs will be generated. +By default with some NICs eg. i40e, the IRQs will land on the same core as that +which is being used by the server process, provided the number of NIC queues is +greater or equal to that lcoreid. This causes contention between the iperf +server process and the IRQs. For optimal performance, it is suggested to pin +the IRQs to their own core. To change the affinity associated with a given IRQ +number, you can 'echo' the desired coremask to the file +/proc/irq/<number>/smp_affinity +For more on SMP affinity, refer to the `Linux kernel documentation`__. + +__ https://www.kernel.org/doc/Documentation/IRQ-affinity.txt diff --git a/manpages.mk b/manpages.mk index dc201484c..54a3a82ad 100644 --- a/manpages.mk +++ b/manpages.mk @@ -104,7 +104,6 @@ utilities/bugtool/ovs-bugtool.8: \ utilities/bugtool/ovs-bugtool.8.in: lib/ovs.tmac: - utilities/ovs-dpctl-top.8: \ utilities/ovs-dpctl-top.8.in \ lib/ovs.tmac @@ -155,8 +154,6 @@ lib/common-syn.man: lib/common.man: lib/ovs.tmac: -lib/ovs.tmac: - utilities/ovs-testcontroller.8: \ utilities/ovs-testcontroller.8.in \ lib/common.man \ -- 2.17.1 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
