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Dmytro Linkin says:
====================
devlink: rate objects API
Resending without RFC.
Currently kernel provides a way to change tx rate of single VF in
switchdev mode via tc-police action. When lots of VFs are configured
management of theirs rates becomes non-trivial task and some grouping
mechanism is required. Implementing such grouping in tc-police will bring
flow related limitations and unwanted complications, like:
- tc-police is a policer and there is a user request for a traffic
shaper, so shared tc-police action is not suitable;
- flows requires net device to be placed on, means "groups" wouldn't
have net device instance itself. Taking into the account previous
point was reviewed a sollution, when representor have a policer and
the driver use a shaper if qdisc contains group of VFs - such approach
ugly, compilated and misleading;
- TC is ingress only, while configuring "other" side of the wire looks
more like a "real" picture where shaping is outside of the steering
world, similar to "ip link" command;
According to that devlink is the most appropriate place.
This series introduces devlink API for managing tx rate of single devlink
port or of a group by invoking callbacks (see below) of corresponding
driver. Also devlink port or a group can be added to the parent group,
where driver responsible to handle rates of a group elements. To achieve
all of that new rate object is added. It can be one of the two types:
- leaf - represents a single devlink port; created/destroyed by the
driver and bound to the devlink port. As example, some driver may
create leaf rate object for every devlink port associated with VF.
Since leaf have 1to1 mapping to it's devlink port, in user space it is
referred as pci/<bus_addr>/<port_index>;
- node - represents a group of rate objects; created/deleted by request
from the userspace; initially empty (no rate objects added). In
userspace it is referred as pci/<bus_addr>/<node_name>, where node name
can be any, except decimal number, to avoid collisions with leafs.
devlink_ops extended with following callbacks:
- rate_{leaf|node}_tx_{share|max}_set
- rate_node_{new|del}
- rate_{leaf|node}_parent_set
KAPI provides:
- creation/destruction of the leaf rate object associated with devlink
port
- destruction of rate nodes to allow a vendor driver to free allocated
resources on driver removal or due to the other reasons when nodes
destruction required
UAPI provides:
- dumping all or single rate objects
- setting tx_{share|max} of rate object of any type
- creating/deleting node rate object
- setting/unsetting parent of any rate object
Added devlink rate object support for netdevsim driver
Issues/open questions:
- Does user need DEVLINK_CMD_RATE_DEL_ALL_CHILD command to clean all
children of particular parent node? For example:
$ devlink port function rate flush netdevsim/netdevsim10/group
- priv pointer passed to the callbacks is a source of bugs; in leaf case
driver can embed rate object into internal structure and use
container_of() on it; in node case it cannot be done since nodes are
created from userspace
v1->v2:
- fixed kernel-doc for devlink_rate_leaf_{create|destroy}()
- s/func/function/ for all devlink port command occurences
v2->v3:
- devlink:
- added devlink_rate_nodes_destroy() function
- netdevsim:
- added call of devlink_rate_nodes_destroy() function
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.