Received-SPF: pass (google.com: domain of linux-kernel+bounces-102673-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
References: <20240223192658.45893-1-rrameshbabu@nvidia.com>
 <20240309084440.299358-1-rrameshbabu@nvidia.com>
 <20240309084440.299358-2-rrameshbabu@nvidia.com>
 <20240312165346.14ec1941@kernel.org>
User-agent: mu4e 1.10.8; emacs 28.2
From: Rahul Rameshbabu <rrameshbabu@nvidia.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: ahmed.zaki@intel.com, 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, 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,
 paul.greenwalt@intel.com, przemyslaw.kitszel@intel.com,
 rdunlap@infradead.org, richardcochran@gmail.com, saeed@kernel.org,
 tariqt@nvidia.com, vadim.fedorenko@linux.dev, vladimir.oltean@nxp.com,
 wojciech.drewek@intel.com
Subject: Re: [PATCH RFC v2 1/6] ethtool: add interface to read Tx hardware
 timestamping statistics
Date: Wed, 13 Mar 2024 17:26:11 -0700
In-reply-to: <20240312165346.14ec1941@kernel.org>
Message-ID: <87le6lbqsa.fsf@nvidia.com>
Content-Type: text/plain
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?us-ascii?Q?xTkZMxdvye7zKCLiidOXfjUyvmoujC+W08LtfaBjiwk0lPBXnQfj0sDPc7DO?=
 =?us-ascii?Q?BrPYjNUbaVRoGEEgl3U7AdUKhEqXXqd4KzFCpohd4JjDdWvLN4ACHCAQTpSu?=
 =?us-ascii?Q?JkGQemky15fEIDZ9tzm2AySuWOq452hqK28FDtdVoa3bE5nmr/J2EKR3i3nj?=
 =?us-ascii?Q?pWm6j1EgPvj58lJhCPqr3Lm0wYTC/En1Shs2GonXkiRWZj4xqcMdM9heQpnR?=
 =?us-ascii?Q?/ZPUis60jFiHQ7FQ+yAmkgtoXYJrVaTvJXfs2KCX4oVc4umcCmaYIdOxbXPY?=
 =?us-ascii?Q?S6ovr+/+XwmobkmUgxb4iyYejmQf8Ka/krk3iN/yva4rtxv++1Mq0rRr8HW5?=
 =?us-ascii?Q?yNX3RkoWJjdaT7R3VrwRxLy642r9V6tYxBxmrxURW2LtmWFjOSrG0KkXrVpE?=
 =?us-ascii?Q?nRiYG033aTDLmddX0o18G6lR47iIXeG+9JMS8VLFheIqaEXqrN8KzZug94Lq?=
 =?us-ascii?Q?Fihpk4C0Rqbw1uTMqtFJZumGHSnL8gRe8twYzeiZQxHd5y2BESg0663vbwFW?=
 =?us-ascii?Q?Qpc9EznHA5/9wUcmT9IYOq4bnZNXH576Eb47Y0Q0fofBZvN/rmpvN26WiF4X?=
 =?us-ascii?Q?Sv2lKH4/iXsaCAfIiB488TtzdPD+OVnij2i5RXHDRfRu0m5bnwTkoHAL1xAX?=
 =?us-ascii?Q?JR4B5cUKW97OwX225sbfhZaU6FNB16i5D5PHjCYmKCWzIp2CsaE+Kv8QUAKw?=
 =?us-ascii?Q?1oWJHQ3/KlftHOxyGcGy8FmTpjSVeIKwR7LDuhrhTrf7qELy/iCgVhwJHKKa?=
 =?us-ascii?Q?9NXPUlR8evtmsqKRYANIyqID6Dw5jiSWSUL5wn9AAhZKZxQkgMCuIl1M4TWu?=
 =?us-ascii?Q?cXoCcwKijhtalglJQaHaKp+Y8TbDQ5lhqgqdY4tE9ft1cJ524SXtSRT6oXZ5?=
 =?us-ascii?Q?hR5EbP0oj+YOhNRSGu1Ju5XVWHjZeR8OrfDmXHNUrsjqSgj4PfR2SZmWNIvK?=
 =?us-ascii?Q?qu2mGwDKbq0zp+mD2InWWbgWrb/GH4mA5dZ6SaW7AUjxJtSZFM+pv1pUga2U?=
 =?us-ascii?Q?ojAhYajUly+yFSVLKi7uuTuKIqvEq2chGMql+m0YP0cB7ixuqBCHVqTDhCDv?=
 =?us-ascii?Q?H/ofeJoij14HO5pHo3mH9EgqnKImVt7fz8g9jrpfvb/H0xbQ6hnUem/pquUJ?=
 =?us-ascii?Q?XmROu4g3QhF2Pg8vCfqJqk0XndnQWV32yI5pWR+m79OxWHgbW13bGxZ5sjjk?=
 =?us-ascii?Q?HR4+o7wLSo+JY27az8/4UONwDjxZy5s2uyWQkZjXyNLNz1wPeC05Xlq2DEu/?=
 =?us-ascii?Q?yvJJUARSXqQXWQCwp/pul5bX27wzrV9dJ94DvDKGjPBDXLumJkV1NqEiC6tS?=
 =?us-ascii?Q?mu3cvj94tSnZ/X5M/CV0r6FjTPizrJRr99g1tFY82+5k7Rhp3+xR7/GMM/DI?=
 =?us-ascii?Q?sqc2AaRqUKlQpzB9fae4/ZO8LaHvt0EJMuvTdG6Yp/NbfPzB7RZdig0+7dcQ?=
 =?us-ascii?Q?nFZtjaGXskg9NW9yBIe+UsSo2DsOw0fIfevXOMgQmt0muWtzQIDWEbyH6kYz?=
 =?us-ascii?Q?SuaT67nVTkUDL5M/fk6VFCT4+z167EqJeVZsAtnXPBysUKYvXLGexsUUnQdH?=
 =?us-ascii?Q?svDeBRDoWo9xVRPzbrYkX/0LjJ3JadnhBDx4PeyqaLHqznNMsXgM5m9ZihFr?=
 =?us-ascii?Q?4Q=3D=3D?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 48fe6f1a-7b7c-4436-90aa-08dc43bda819
X-MS-Exchange-CrossTenant-AuthSource: BYAPR12MB2743.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Mar 2024 00:28:22.9070
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: hrohBwDZpAubEMbGaVn48AIkHxTekCzt/zpuMQ4LqMh2GUIzgwu/01JnsaHiTVzIUo6zqdZ1mv4U+O7Hq+iJ2w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7840

On Tue, 12 Mar, 2024 16:53:46 -0700 Jakub Kicinski <kuba@kernel.org> wrote:
> On Sat,  9 Mar 2024 00:44:35 -0800 Rahul Rameshbabu wrote:
>> Multiple network devices that support hardware timestamping appear to have
>> common behavior with regards to timestamp handling. Implement common Tx
>> hardware timestamping statistics in a tx_stats struct_group. Common Rx
>> hardware timestamping statistics can subsequently be implemented in a
>> rx_stats struct_group for ethtool_ts_stats.
>
>>  Documentation/netlink/specs/ethtool.yaml | 20 +++++++++
>>  include/linux/ethtool.h                  | 21 ++++++++++
>>  include/uapi/linux/ethtool_netlink.h     | 15 +++++++
>>  net/ethtool/tsinfo.c                     | 52 +++++++++++++++++++++++-
>>  4 files changed, 107 insertions(+), 1 deletion(-)
>
> Feels like we should mention the new stats somehow in 
> Documentation/networking/ethtool-netlink.rst
>
>> diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
>> index 197208f419dc..f99b003c78c0 100644
>> --- a/Documentation/netlink/specs/ethtool.yaml
>> +++ b/Documentation/netlink/specs/ethtool.yaml
>> @@ -559,6 +559,21 @@ attribute-sets:
>>        -
>>          name: tx-lpi-timer
>>          type: u32
>> +  -
>> +    name: ts-stat
>> +    attributes:
>> +      -
>> +        name: pad
>> +        type: pad
>
> You can remove the pad entry, and...
>
>> +      -
>> +        name: tx-pkts
>> +        type: u64
>
> ...use the uint type for the stats
>
>> +      -
>> +        name: tx-lost
>> +        type: u64
>> +      -
>> +        name: tx-err
>> +        type: u64
>>    -
>>      name: tsinfo
>>      attributes:
>
>> +/**
>> + * struct ethtool_ts_stats - HW timestamping statistics
>> + * @tx_stats: struct group for TX HW timestamping
>> + *	@pkts: Number of packets successfully timestamped by the queried
>> + *	      layer.
>> + *	@lost: Number of packet timestamps that failed to get applied on a
>> + *	      packet by the queried layer.
>> + *	@err: Number of timestamping errors that occurred on the queried
>> + *	     layer.
>
> the kdocs for @lost and @err are not very clear

Makes sense given that these are stale and should have been changed
between my v1 and v2. Here is my new attempt at this.

 /**
  * struct ethtool_ts_stats - HW timestamping statistics
  * @tx_stats: struct group for TX HW timestamping
  *	@pkts: Number of packets successfully timestamped by the hardware.
  *	@lost: Number of hardware timestamping requests where the timestamping
  *            information from the hardware never arrived for submission with
  *            the skb.
  *	@err: Number of arbitrary timestamp generation error events that the
  *           hardware encountered.
  */


>
>> + * @get_ts_stats: Query the device hardware timestamping statistics.
>
> Let's copy & paste the "Drivers must not zero" text in here?
> People seem to miss that requirement anyway, but at least we'll
> have something to point at in review.
>
>> +enum {
>> +	ETHTOOL_A_TS_STAT_UNSPEC,
>> +	ETHTOOL_A_TS_STAT_PAD,
>> +
>> +	ETHTOOL_A_TS_STAT_TX_PKT,			/* array, u64 */
>> +	ETHTOOL_A_TS_STAT_TX_LOST,			/* array, u64 */
>> +	ETHTOOL_A_TS_STAT_TX_ERR,			/* array, u64 */
>
> I don't think these are arrays.

Sorry, copy-paste mistake from FEC stats....

>
>> +
>> +	/* add new constants above here */
>> +	__ETHTOOL_A_TS_STAT_CNT,
>> +	ETHTOOL_A_TS_STAT_MAX = (__ETHTOOL_A_TS_STAT_CNT - 1)
>> +
>> +};

Agreed with all the comments here. Have accounted for them in my patches
for my next submission (aiming for non-RFC once the net-next window is
open again).

--
Thanks,

Rahul Rameshbabu