[dpdk-users] KNI optimization techniques

["Sawant, Sunil (Artesyn)" <Sunil.Sawant@Artesyn.com>]

Hi,

Requirement - Looking for KNI optimization techniques to speed-up packet transfer from DPDK Port to it corresponding Ethernet interface ( further to DHCP server on Host machine).

Case - DSPs, while booting, try to fetch the boot image on the Host machine. They use TFTP protocol to boot. Now, DSPs fail to boot as the DHCP DISCOVER packets sent by DSPs are delayed over KNI. From the time, the DISCOVER is generated to the time the host sends DHCP OFFERs to the DSPs, a huge time delay is observed (~ 4s).
The boot process works fine without DPDK.

Environment - DPDK 2.1.0 on RHEL 6.4, 64 bit, 8 cores.

Other details -
MemTotal:       32961560 kB
MemFree:        23676720 kB
isolcpus=3,5,7 default_hugepagesz=1G hugepagesz=1G hugepages=8

Optimizations done -

*        Increased Hugepage size

*        Isolated CPU cores

*        Tweaked BIOS parameters - http://dpdk.org/doc/guides-16.04/linux_gsg/nic_perf_intel_platform.html

*        Having multiple kthread for each port

*        Making KNI threads RT and having highest priority

The delay is persistent even after all the above optimizations are done. Could anyone please suggest more/better optimizations ? Is there any way where KNI just transmits the packets the moment it receives (without buffering ) ?

Thanks,
Sunil D. Sawant