[ovs-dev] [PATCH v11 1/3] netdev: Add optional qfill output parameter to rxq_recv()

Ben Pfaff blp at ovn.org
Thu Apr 12 16:36:34 UTC 2018

On Thu, Apr 12, 2018 at 05:32:11PM +0200, Jan Scheurich wrote:
> If the caller provides a non-NULL qfill pointer and the netdev
> implemementation supports reading the rx queue fill level, the rxq_recv()
> function returns the remaining number of packets in the rx queue after
> reception of the packet burst to the caller. If the implementation does
> not support this, it returns -ENOTSUP instead. Reading the remaining queue
> fill level should not substantilly slow down the recv() operation.
> A first implementation is provided for ethernet and vhostuser DPDK ports
> in netdev-dpdk.c.
> This output parameter will be used in the upcoming commit for PMD
> performance metrics to supervise the rx queue fill level for DPDK
> vhostuser ports.

Thanks for working on the generic netdev layer.

I wasn't sure what a qfill was, so I looked at the comment on the
function that returned it and it says that it is a "queue fill level".
I can kind of guess what that is, but maybe it should be spelled out a
little more.  For example, is it the number of packets currently waiting
to be received?  (Maybe it is the number of bytes, who knows.)  So, I
suggest making the comment just a little more explicit.



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