Re: Pure polling mode for netdevices

On Fri, 2016-10-21 at 13:03 -0500, Zach Brown wrote:

Is there a way to get NAPI to poll all the time?
Or just any way to get netdevices to use only polling and no interrupts?

We have some rt targets where the jitter can be improved by disabling
interrupts and using just polling. In these cases we're okay with the
performance downsides that come with polling.

In particular we already have an implementation for the cadence macb driver
that does only polling mode and have verified that it improves the
jitter.

We're hoping for a more general existing solution or at the very least a
solution that would be accepted upstream. Any thoughts?

This is not yet done, although you could use busy poll infrastructure to
get this without a kernel change.

Open as many TCP flows are necessary to traverse all the queues you care
about, then loop on recvmsg() to trigger NAPI polling.