Date:   Wed, 27 Dec 2017 08:28:50 +0000
From:   Yuval Mintz <yuvalm@...lanox.com>
To:     Jiri Pirko <jiri@...nulli.us>,
        David Ahern <dsa@...ulusnetworks.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Arkadi Sharshevsky <arkadis@...lanox.com>,
        mlxsw <mlxsw@...lanox.com>, "andrew@...n.ch" <andrew@...n.ch>,
        "vivien.didelot@...oirfairelinux.com" 
        <vivien.didelot@...oirfairelinux.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "michael.chan@...adcom.com" <michael.chan@...adcom.com>,
        "ganeshgr@...lsio.com" <ganeshgr@...lsio.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Matan Barak <matanb@...lanox.com>,
        "Leon Romanovsky" <leonro@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        "jakub.kicinski@...ronome.com" <jakub.kicinski@...ronome.com>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "simon.horman@...ronome.com" <simon.horman@...ronome.com>,
        "pieter.jansenvanvuuren@...ronome.com" 
        <pieter.jansenvanvuuren@...ronome.com>,
        "john.hurley@...ronome.com" <john.hurley@...ronome.com>,
        "alexander.h.duyck@...el.com" <alexander.h.duyck@...el.com>,
        "linville@...driver.com" <linville@...driver.com>,
        "gospo@...adcom.com" <gospo@...adcom.com>,
        "steven.lin1@...adcom.com" <steven.lin1@...adcom.com>,
        Or Gerlitz <ogerlitz@...lanox.com>,
        "roopa@...ulusnetworks.com" <roopa@...ulusnetworks.com>
Subject: RE: [patch net-next v2 00/10] Add support for resource abstraction

> >> Many of the ASIC's internal resources are limited and are shared between
> >> several hardware procedures. For example, unified hash-based memory
> can
> >> be used for many lookup purposes, like FDB and LPM. In many cases the
> user
> >> can provide a partitioning scheme for such a resource in order to perform
> >> fine tuning for his application. In such cases performing driver reload is
> >> needed for the changes to take place, thus this patchset also adds support
> >> for hot reload.
> >>
> >> Such an abstraction can be coupled with devlink's dpipe interface, which
> >> models the ASIC's pipeline as a graph of match/action tables. By modeling
> >> the hardware resource object, and by coupling it to several dpipe tables,
> >> further visibility can be achieved in order to debug ASIC-wide issues.
> >>
> >> The proposed interface will provide the user the ability to understand the
> >> limitations of the hardware, and receive notification regarding its
> occupancy.
> >> Furthermore, monitoring the resource occupancy can be done in real-time
> and
> >> can be useful in many cases.
> >
> >In the last RFC (not v1, but RFC) I asked for some kind of description
> >for each resource, and you and Arkadi have pushed back. Let's walk
> >through an example to see what I mean:
> >
> >$ devlink resource show pci/0000:03:00.0
> >pci/0000:03:00.0:
> >  name kvd size 245760 size_valid true
> >  resources:
> >    name linear size 98304 occ 0
> >    name hash_double size 60416
> >    name hash_single size 87040
> >
> >So this 2700 has 3 resources that can be managed -- some table or
> >resource or something named 'kvd' with linear, hash_double and
> >hash_single sub-resources. What are these names referring too? The above
> >output gives no description, and 'kvd' is not an industry term. Further,
> 
> This are internal resources specific to the ASIC. Would you like some
> description to each or something like that?
> 
> 
> >what are these sizes that a user can control? The output contains no
> >units, no description, nothing. In short, the above output provides
> >random numbers associated with random names.
> 
> Units are now exposed from kernel, just this version of iproute2 patch
> does not display it.
> 
> 
> >
> >I can see dpipe tables exported by this device:
> >
> >$ devlink dpipe header show pci/0000:03:00.0
> >
> >pci/0000:03:00.0:
> >  name mlxsw_meta
> >  field:
> >    name erif_port bitwidth 32 mapping_type ifindex
> >    name l3_forward bitwidth 1
> >    name l3_drop bitwidth 1
> >    name adj_index bitwidth 32
> >    name adj_size bitwidth 32
> >    name adj_hash_index bitwidth 32
> >
> >  name ipv6
> >  field:
> >    name destination ip bitwidth 128
> >
> >  name ipv4
> >  field:
> >    name destination ip bitwidth 32
> >
> >  name ethernet
> >  field:
> >    name destination mac bitwidth 48
> >
> >but none mention 'kvd' or 'linear' or 'hash" and none of the other
> >various devlink options:
> >
> >$ devlink
> >Usage: devlink [ OPTIONS ] OBJECT { COMMAND | help }
> >where  OBJECT := { dev | port | sb | monitor | dpipe }
> >
> >seem to related to resources.
> >
> >So how does a user know what they are controlling by this 'resource'
> >option? Is the user expected to have a PRM or user guide on hand for the
> >specific device model that is being configured?
> 
> The relation of specific dpipe table to specific resource is exposed by
> the kernel as well. Probably the iproute2 patch just does not display
> it.

It does, just under 'table' and not under 'header'. E.g.:

# ./devlink/devlink dpipe -j -p table show pci/0000:03:00.0
...
            },{
                "resource_path": "/kvd/hash_single",
                "name": "mlxsw_host4",
                "size": 0,
                "counters_enabled": "false",
                "match": [{
                        "type": "field_exact",
                        "header": "mlxsw_meta",
                        "field": "erif_port",
                        "mapping": "ifindex"
                    },{
                        "type": "field_exact",
                        "header": "ipv4",
                        "field": "destination ip"
                    }
                ],
                "action": [{
                        "type": "field_modify",
                        "header": "ethernet",
                        "field": "destination mac"
                    }
                ]
            },{
...

> 
> 
> >
> >Again, I have no objections to kvd, linear, hash, etc terms as they do
> >relate to Mellanox products. But kvd/linear, for example, does correlate
> >to industry standard concepts in some way. My request is that the
> >resource listing guide the user in some way, stating what these
> >resources mean.
> 
> So the showed relation to dpipe table would be enougn or you would still
> like to see some description? I don't like the description concept here
> as the relations to dpipe table should tell user exactly what he needs
> to know.
> 
> 
> >
> >IMO the above output is not user friendly and having to keep a PRM on
> >hand for each device model is not a realistic solution.

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