RE: [EXTERNAL] Re: [PATCH net-next v5 1/3] net: ethtool: add ethtool COALESCE_RX_CQE_FRAMES/NSECS

[Haiyang Zhang]

> -----Original Message-----
> From: Jakub Kicinski <kuba@xxxxxxxxxx>
> Sent: Monday, March 16, 2026 11:05 PM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxxxxxxxx>
> Cc: linux-hyperv@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Andrew Lunn
> <andrew@xxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; Simon Horman
> <horms@xxxxxxxxxx>; Donald Hunter <donald.hunter@xxxxxxxxx>; Jonathan
> Corbet <corbet@xxxxxxx>; Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>; Kory
> Maincent (Dent Project) <kory.maincent@xxxxxxxxxxx>; Gal Pressman
> <gal@xxxxxxxxxx>; Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>; Vadim
> Fedorenko <vadim.fedorenko@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> linux-doc@xxxxxxxxxxxxxxx; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Paul
> Rosswurm <paulros@xxxxxxxxxxxxx>
> Subject: [EXTERNAL] Re: [PATCH net-next v5 1/3] net: ethtool: add ethtool
> COALESCE_RX_CQE_FRAMES/NSECS
> 
> On Thu, 12 Mar 2026 12:37:04 -0700 Haiyang Zhang wrote:
> > +Rx CQE coalescing allows multiple received packets to be coalesced into
> a single
> > +Completion Queue Entry (CQE). ``ETHTOOL_A_COALESCE_RX_CQE_FRAMES``
> describes the
> > +maximum number of frames that can be coalesced into a CQE.
> > +``ETHTOOL_A_COALESCE_RX_CQE_NSECS`` describes max time in nanoseconds
> after the
> > +first packet arrival in a coalesced CQE to be sent.
> 
> Looks good overall, can we broaden the language a bit?
> Replace "a single Completion Queue Entry (CQE)" with "a single
> Completion Queue Entry (CQE) or descriptor write back"?
Sure.

> I'm assuming your devices don't coalesce CQE writes.
> For non-RDMA devices the notion of CQE is a bit foreign but
> descriptor write back coalescing serves similar purpose.
> In either case host can't see the frame even if it's busy
> polling.
> 
> So:
> 
> Rx CQE coalescing allows multiple received packets to be coalesced
> into a single Completion Queue Entry (CQE) or descriptor writeback.
> ``ETHTOOL_A_COALESCE_RX_CQE_FRAMES`` describes the maximum number of
> frames that can be coalesced into a CQE or writeback.
> ``ETHTOOL_A_COALESCE_RX_CQE_NSECS`` describes max time in nanoseconds
> after the first packet arrival in a coalesced CQE to be sent.
Will do.

Thanks,
- Haiyang