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From: "Keller, Jacob E" <jacob.e.keller@intel.com>
To: Jakub Kicinski <kuba@kernel.org>, Rahul Rameshbabu
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Subject: RE: [PATCH RFC v2 1/6] ethtool: add interface to read Tx hardware
 timestamping statistics
Thread-Topic: [PATCH RFC v2 1/6] ethtool: add interface to read Tx hardware
 timestamping statistics
Thread-Index: AQHacf4WBtsLQqAxuESeM9XGdjpqArE0zQ4AgAGbY4CAAAQtgIAAAqmAgAAN34CAAQ7JQA==
Date: Thu, 14 Mar 2024 17:50:10 +0000
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References: <20240223192658.45893-1-rrameshbabu@nvidia.com>
	<20240309084440.299358-1-rrameshbabu@nvidia.com>
	<20240309084440.299358-2-rrameshbabu@nvidia.com>
	<20240312165346.14ec1941@kernel.org>	<87le6lbqsa.fsf@nvidia.com>
	<20240313174107.68ca4ff1@kernel.org>	<87h6h9bpm1.fsf@nvidia.com>
 <20240313184017.794a2044@kernel.org>
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> -----Original Message-----
> From: Jakub Kicinski <kuba@kernel.org>
> Sent: Wednesday, March 13, 2024 6:40 PM
> To: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Cc: Zaki, Ahmed <ahmed.zaki@intel.com>; Lobakin, Aleksander
> <aleksander.lobakin@intel.com>; alexandre.torgue@foss.st.com;
> andrew@lunn.ch; corbet@lwn.net; davem@davemloft.net; dtatulea@nvidia.com;
> edumazet@google.com; gal@nvidia.com; hkallweit1@gmail.com; Keller, Jacob =
E
> <jacob.e.keller@intel.com>; jiri@resnulli.us; joabreu@synopsys.com;
> justinstitt@google.com; kory.maincent@bootlin.com; leon@kernel.org; linux=
-
> doc@vger.kernel.org; linux-kernel@vger.kernel.org; liuhangbin@gmail.com;
> maxime.chevallier@bootlin.com; netdev@vger.kernel.org; pabeni@redhat.com;
> Greenwalt, Paul <paul.greenwalt@intel.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@intel.com>; rdunlap@infradead.org;
> richardcochran@gmail.com; saeed@kernel.org; tariqt@nvidia.com;
> vadim.fedorenko@linux.dev; vladimir.oltean@nxp.com; Drewek, Wojciech
> <wojciech.drewek@intel.com>
> Subject: Re: [PATCH RFC v2 1/6] ethtool: add interface to read Tx hardwar=
e
> timestamping statistics
>=20
> On Wed, 13 Mar 2024 17:50:39 -0700 Rahul Rameshbabu wrote:
> > > Should we give some guidance to drivers which "ignore" time stamping
> > > requests if they used up all the "slots"? Even if just temporary unti=
l
> > > they are fixed? Maybe we can add after all the fields something like:
> > >
> > >   For drivers which ignore further timestamping requests when there a=
re
> > >   too many in flight, the ignored requests are currently not counted =
by
> > >   any of the statistics.
> >
> > I was actually thinking it would be better to merge them into the error
> > counter temporarily. Reason being is that in the case Intel notices tha=
t
> > their slots are full, they just drop traffic from my understanding
> > today. If the error counters increment in that situation, it helps with
> > the debug to a degree. EBUSY is an error in general.
>=20
> That works, too, let's recommend it (FWIW no preference whether
> in the entry for @err or somewhere separately in the kdoc).

We don't drop traffic, we send the packets just fine.. We just never report=
 a timestamp for them, since we don't program the hardware to capture that =
timestamp.