Added information about output packet batching and a way to configure 'tx-flush-interval'.
Signed-off-by: Ilya Maximets <[email protected]> --- This patch is made on top of v7 of Output Batching patch-set: https://mail.openvswitch.org/pipermail/ovs-dev/2017-December/341936.html This patch sent as RFC separately from the rest of the series because it's new and I don't want this to block accepting of the main series. It'll be much easier to fix/rebase just this patch without re-sending of the whole patch-set. Documentation/intro/install/dpdk.rst | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Documentation/intro/install/dpdk.rst b/Documentation/intro/install/dpdk.rst index 3fecb5c..b0bb76e 100644 --- a/Documentation/intro/install/dpdk.rst +++ b/Documentation/intro/install/dpdk.rst @@ -568,6 +568,30 @@ not needed i.e. jumbo frames are not needed, it can be forced off by adding chains of descriptors it will make more individual virtio descriptors available for rx to the guest using dpdkvhost ports and this can improve performance. +Output Packet Batching +~~~~~~~~~~~~~~~~~~~~~~ + +To get advantages of batched send functions OVS collects packets in +intermediate queues before sending. This allows to use single send even for +packets matched by different flows but having same output action. Furthermore, +OVS is able to collect packets for some reasonable amount of time before +sending to use batched send in case where input batches are small. + +``tx-flush-interval`` config could be used to specify the time in microseconds +that a packet can wait in an output queue for sending (default is ``0``):: + + $ ovs-vsctl set Open_vSwitch . other_config:tx-flush-interval=50 + +Lower values decreases latency while higher values may be useful to achieve +higher performance. For example, increasing of ``tx-flush-interval`` can be +used to decrease number of interrupts for interrupt based guest drivers. +This may significantly affect the performance. Zero value means immediate +send at the end of processing of a single input batch. + +Average number of packets per output batch could be checked in PMD stats:: + + $ ovs-appctl dpif-netdev/pmd-stats-show + Limitations ------------ -- 2.7.4 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
