> On Mar 26, 2017, at 5:33 PM, Michael Williams <[email protected]> wrote:
>
> What are the advantages of running the kernel verses the user mode switch?
I assume you're specifically asking about running DPDK in userspace. There are
certain traffic patterns that can be significantly faster by bypassing the
kernel and handling directly in userspace. But, by bypassing the kernel, you
miss out on the functionality provided by the kernel, so those must be
recreated. Some examples include:
- QoS
- Connection tracking (for firewalls) and NAT
- An IP stack (for tunnel termination)
- Some NIC offloads
Those features are being added, but not all of them are complete yet, so if you
need a particular functionality, you may need to check whether it has all the
features you need.
In the case of DPDK, there can be restrictions on the CPUs and NICs that are
supported. Also, for optimal performance, DPDK typically uses dedicated cores,
but there's options to run in an interrupt-driven model.
--Justin
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