On Mon, 12 Jan 2026 21:01:59 +0000 Haiyang Zhang wrote:

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Our NIC can have up to 4 RX packets on 1 CQE. To support this feature,
check and process the type CQE_RX_COALESCED_4. The default setting is
disabled, to avoid possible regression on latency.

And add ethtool handler to switch this feature. To turn it on, run:
  ethtool -C <nic> rx-frames 4
To turn it off:
  ethtool -C <nic> rx-frames 1  

Exposing just rx frame count, and only two values is quite unusual.
Please explain in more detail the coalescing logic of the device.  

Our NIC device only supports coalescing on RX. And when it's disabled each
RX CQE indicates 1 RX packet; when enabled each RX CQE indicates up to 4 packets.

I get that. What is the logic for combining 4 packets into a single
completion? How does it work? Your commit message mentions "regression
on latency" - what is the bound on that regression?