From: Jiri Pirko <jiri@resnulli.us>
To: Michal Kubecek <mkubecek@suse.cz>
Cc: netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
Jakub Kicinski <jakub.kicinski@netronome.com>,
Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
John Linville <linville@tuxdriver.com>,
Stephen Hemminger <stephen@networkplumber.org>,
Johannes Berg <johannes@sipsolutions.net>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v6 04/15] ethtool: introduce ethtool netlink interface
Date: Mon, 8 Jul 2019 21:28:37 +0200 [thread overview]
Message-ID: <20190708192837.GE2282@nanopsycho.orion> (raw)
In-Reply-To: <20190708192629.GD2282@nanopsycho.orion>
Mon, Jul 08, 2019 at 09:26:29PM CEST, jiri@resnulli.us wrote:
>Mon, Jul 08, 2019 at 07:27:29PM CEST, mkubecek@suse.cz wrote:
>>On Wed, Jul 03, 2019 at 10:41:51AM +0200, Jiri Pirko wrote:
>>> Tue, Jul 02, 2019 at 04:52:41PM CEST, mkubecek@suse.cz wrote:
>>> >On Tue, Jul 02, 2019 at 02:25:21PM +0200, Jiri Pirko wrote:
>>> >> Tue, Jul 02, 2019 at 01:49:59PM CEST, mkubecek@suse.cz wrote:
>>> >> >+
>>> >> >+ ETHTOOL_A_HEADER_DEV_INDEX (u32) device ifindex
>>> >> >+ ETHTOOL_A_HEADER_DEV_NAME (string) device name
>>> >> >+ ETHTOOL_A_HEADER_INFOMASK (u32) info mask
>>> >> >+ ETHTOOL_A_HEADER_GFLAGS (u32) flags common for all requests
>>> >> >+ ETHTOOL_A_HEADER_RFLAGS (u32) request specific flags
>>> >> >+
>>> >> >+ETHTOOL_A_HEADER_DEV_INDEX and ETHTOOL_A_HEADER_DEV_NAME identify the device
>>> >> >+message relates to. One of them is sufficient in requests, if both are used,
>>> >> >+they must identify the same device. Some requests, e.g. global string sets, do
>>> >> >+not require device identification. Most GET requests also allow dump requests
>>> >> >+without device identification to query the same information for all devices
>>> >> >+providing it (each device in a separate message).
>>> >> >+
>>> >> >+Optional info mask allows to ask only for a part of data provided by GET
>>> >>
>>> >> How this "infomask" works? What are the bits related to? Is that request
>>> >> specific?
>>> >
>>> >The interpretation is request specific, the information returned for
>>> >a GET request is divided into multiple parts and client can choose to
>>> >request one of them (usually one). In the code so far, infomask bits
>>> >correspond to top level (nest) attributes but I would rather not make it
>>> >a strict rule.
>>>
>>> Wait, so it is a matter of verbosity? If you have multiple parts and the
>>> user is able to chose one of them, why don't you rather have multiple
>>> get commands, one per bit. This infomask construct seems redundant to me.
>>
>>I thought it was a matter of verbosity because it is a very basic
>>element of the design, it was even advertised in the cover letter among
>>the basic ideas, it has been there since the very beginning and in five
>>previous versions through year and a half, noone did question it. That's
>>why I thought you objected against unclear description, not against the
>>concept as such.
>>
>>There are two reasons for this design. First is to reduce the number of
>>requests needed to get the information. This is not so much a problem of
>>ethtool itself; the only existing commands that would result in multiple
>>request messages would be "ethtool <dev>" and "ethtool -s <dev>". Maybe
>>also "ethtool -x/-X <dev>" but even if the indirection table and hash
>>key have different bits assigned now, they don't have to be split even
>>if we split other commands. It may be bigger problem for daemons wanting
>>to keep track of system configuration which would have to issue many
>>requests whenever a new device appears.
>>
>>Second reason is that with 8-bit genetlink command/message id, the space
>>is not as infinite as it might seem. I counted quickly, right now the
>>full series uses 14 ids for kernel messages, with split you propose it
>>would most likely grow to 44. For full implementation of all ethtool
>>functionality, we could get to ~60 ids. It's still only 1/4 of the
>>available space but it's not clear what the future development will look
>>like. We would certainly need to be careful not to start allocating new
>>commands for single parameters and try to be foreseeing about what can
>>be grouped together. But we will need to do that in any case.
>>
>>On kernel side, splitting existing messages would make some things a bit
>>easier. It would also reduce the number of scenarios where only part of
>>requested information is available or only part of a SET request fails.
>
>Okay, I got your point. So why don't we look at if from the other angle.
>Why don't we have only single get/set command that would be in general
>used to get/set ALL info from/to the kernel. Where we can have these
>bits (perhaps rather varlen bitfield) to for user to indicate which data
>is he interested in? This scales. The other commands would be
>just for action.
>
>Something like RTM_GETLINK/RTM_SETLINK. Makes sense?
+ I think this might safe a lot of complexicity aroung your proposed
inner ops.
>
>
>>
>>Michal
next prev parent reply other threads:[~2019-07-08 19:28 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 11:49 [PATCH net-next v6 00/15] ethtool netlink interface, part 1 Michal Kubecek
2019-07-02 11:49 ` [PATCH net-next v6 01/15] rtnetlink: provide permanent hardware address in RTM_NEWLINK Michal Kubecek
2019-07-02 11:57 ` Jiri Pirko
2019-07-02 14:55 ` Stephen Hemminger
2019-07-02 16:35 ` Michal Kubecek
2019-07-02 11:49 ` [PATCH net-next v6 02/15] netlink: rename nl80211_validate_nested() to nla_validate_nested() Michal Kubecek
2019-07-02 12:03 ` Jiri Pirko
2019-07-02 12:15 ` Johannes Berg
2019-07-02 12:15 ` Johannes Berg
2019-07-02 11:49 ` [PATCH net-next v6 03/15] ethtool: move to its own directory Michal Kubecek
2019-07-02 11:49 ` [PATCH net-next v6 04/15] ethtool: introduce ethtool netlink interface Michal Kubecek
2019-07-02 12:25 ` Jiri Pirko
2019-07-02 14:52 ` Michal Kubecek
2019-07-03 8:41 ` Jiri Pirko
2019-07-08 17:27 ` Michal Kubecek
2019-07-08 18:12 ` Johannes Berg
2019-07-08 19:26 ` Jiri Pirko
2019-07-08 19:28 ` Jiri Pirko [this message]
2019-07-08 20:22 ` Michal Kubecek
2019-07-09 13:42 ` Jiri Pirko
2019-07-10 12:12 ` Michal Kubecek
2019-07-03 1:29 ` Jakub Kicinski
2019-07-03 6:35 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 05/15] ethtool: helper functions for " Michal Kubecek
2019-07-02 13:05 ` Jiri Pirko
2019-07-02 16:34 ` Michal Kubecek
2019-07-03 1:28 ` Jakub Kicinski
2019-07-03 10:04 ` Jiri Pirko
2019-07-03 11:13 ` Michal Kubecek
2019-07-08 12:22 ` Michal Kubecek
2019-07-08 14:40 ` Jiri Pirko
2019-07-03 1:37 ` Jakub Kicinski
2019-07-03 7:23 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 06/15] ethtool: netlink bitset handling Michal Kubecek
2019-07-03 11:49 ` Jiri Pirko
2019-07-03 13:44 ` Johannes Berg
2019-07-03 14:37 ` Jiri Pirko
2019-07-04 12:07 ` Johannes Berg
2019-07-03 18:18 ` Michal Kubecek
2019-07-04 8:04 ` Jiri Pirko
2019-07-04 11:52 ` Michal Kubecek
2019-07-04 12:03 ` Johannes Berg
2019-07-04 12:17 ` Michal Kubecek
2019-07-04 12:21 ` Johannes Berg
2019-07-04 12:53 ` Michal Kubecek
2019-07-04 13:10 ` Johannes Berg
2019-07-04 14:31 ` Andrew Lunn
2019-07-09 14:18 ` Jiri Pirko
2019-07-10 12:38 ` Michal Kubecek
2019-07-10 12:59 ` Jiri Pirko
2019-07-10 14:37 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 07/15] ethtool: support for netlink notifications Michal Kubecek
2019-07-03 13:33 ` Jiri Pirko
2019-07-03 14:16 ` Michal Kubecek
2019-07-04 8:06 ` Jiri Pirko
2019-07-03 13:39 ` Johannes Berg
2019-07-03 14:18 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 08/15] ethtool: move string arrays into common file Michal Kubecek
2019-07-03 13:44 ` Jiri Pirko
2019-07-03 14:37 ` Michal Kubecek
2019-07-04 8:09 ` Jiri Pirko
2019-07-02 11:50 ` [PATCH net-next v6 09/15] ethtool: generic handlers for GET requests Michal Kubecek
2019-07-03 14:25 ` Jiri Pirko
2019-07-03 17:53 ` Michal Kubecek
2019-07-04 8:45 ` Jiri Pirko
2019-07-04 8:49 ` Jiri Pirko
2019-07-04 9:28 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 10/15] ethtool: provide string sets with STRSET_GET request Michal Kubecek
2019-07-04 8:17 ` Jiri Pirko
2019-07-02 11:50 ` [PATCH net-next v6 11/15] ethtool: provide link mode names as a string set Michal Kubecek
2019-07-03 2:04 ` Jakub Kicinski
2019-07-03 2:11 ` Jakub Kicinski
2019-07-03 7:38 ` Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 12/15] ethtool: provide link settings and link modes in SETTINGS_GET request Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 13/15] ethtool: add standard notification handler Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 14/15] ethtool: set link settings and link modes with SETTINGS_SET request Michal Kubecek
2019-07-02 11:50 ` [PATCH net-next v6 15/15] ethtool: provide link state in SETTINGS_GET request Michal Kubecek
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