[dpdk-dev] What is the max size of packets rte_eth_tx_burst() can send practically/theoritically?

[dpdk-dev] What is the max size of packets rte_eth_tx_burst() can send practically/theoritically?

[Joo Kim]

Hello,


For example, as I understand,  ovs-dpdk code  uses a buffer of size 32
when it transmits via rte_eth_tx_burst().

I think it can transmit more packets in a bust.
I know there should be a balance between throughput and latency. But, I am
wondering what max size packets  a dpdk application can give  to
rte_eth_tx_burst()  practically/theoretically?
(I see some max macro in ixgbe_rxtx.h)

Thanks

Re: [dpdk-dev] What is the max size of packets rte_eth_tx_burst() can send practically/theoritically?

[Stephen Hemminger]

On Tue, 28 Feb 2017 20:28:21 -0800
Joo Kim <itsolution@gmail.com> wrote:

> Hello,
> 
> 
> For example, as I understand,  ovs-dpdk code  uses a buffer of size 32
> when it transmits via rte_eth_tx_burst().
> 
> I think it can transmit more packets in a bust.
> I know there should be a balance between throughput and latency. But, I am
> wondering what max size packets  a dpdk application can give  to
> rte_eth_tx_burst()  practically/theoretically?
> (I see some max macro in ixgbe_rxtx.h)
> 
> Thanks

You could theoretically transmit a burst size up to the configured number of TX descriptors.
The downside is you will add latency and have to handle the TX ring getting full more often.
Bigger burst sizes really don't win that much. 50% of the gain happens by just sending 2 at a time.