[dpdk-dev] [PATCH v7 1/2] ethdev: add flow shared action API

Andrew Rybchenko andrew.rybchenko at oktetlabs.ru
Wed Oct 14 08:49:34 CEST 2020


Hi Andrey,

On 10/13/20 11:06 PM, Andrey Vesnovaty wrote:
> Hi Andrew.
> 
> Thanks for the input.
> All spelling & rephrases will be applied  PSB for the rest.
> Will publish v8 very soon.
> 
> Thanks,
> Andrey
> 
>> -----Original Message-----
>> From: Andrew Rybchenko <Andrew.Rybchenko at oktetlabs.ru>
>> Sent: Monday, October 12, 2020 5:19 PM
>> To: Andrey Vesnovaty <andreyv at nvidia.com>; dev at dpdk.org
>> Cc: jer at marvell.com; jerinjacobk at gmail.com; NBU-Contact-Thomas Monjalon
>> <thomas at monjalon.net>; ferruh.yigit at intel.com;
>> stephen at networkplumber.org; bruce.richardson at intel.com; Ori Kam
>> <orika at nvidia.com>; Slava Ovsiienko <viacheslavo at nvidia.com>;
>> andrey.vesnovaty at gmail.com; mdr at ashroe.eu; nhorman at tuxdriver.com;
>> ajit.khaparde at broadcom.com; samik.gupta at broadcom.com
>> Subject: Re: [dpdk-dev] [PATCH v7 1/2] ethdev: add flow shared action API
>>
>> "add flow shared action API"
>>
>> Is flow shared? May be "add shared actions to flow API".
> 
> Accepted, will update commit message.
>>
>> On 10/8/20 2:51 PM, Andrey Vesnovaty wrote:
>>> This commit introduces extension of DPDK flow action API enabling
>>
>> "This commit" and "DPDK" are not necessary in description.
>> It is a commit description and the patch is to DPDK tree.
>> Consider just:
>> "Introduce extension of flow action API enabling..."
> 
> Accepted, will update commit message.
>>
>>> sharing of single rte_flow_action in multiple flows. The API intended for
>>> PMDs, where multiple HW offloaded flows can reuse the same HW
>>> essence/object representing flow action and modification of such an
>>> essence/object affects all the rules using it.
>>>
>>> Motivation and example
>>> ===
>>> Adding or removing one or more queues to RSS used by multiple flow rules
>>> imposes per rule toll for current DPDK flow API; the scenario requires
>>> for each flow sharing cloned RSS action:
>>> - call `rte_flow_destroy()`
>>> - call `rte_flow_create()` with modified RSS action
>>>
>>> API for sharing action and its in-place update benefits:
>>> - reduce the overhead of multiple RSS flow rules reconfiguration
>>> - optimize resource utilization by sharing action across multiple
>>>   flows
>>>
>>> Change description
>>> ===
>>>
>>> Shared action
>>> ===
>>> In order to represent flow action shared by multiple flows new action
>>> type RTE_FLOW_ACTION_TYPE_SHARED is introduced (see `enum
>>> rte_flow_action_type`).
>>> Actually the introduced API decouples action from any specific flow and
>>> enables sharing of single action by its handle across multiple flows.
>>>
>>> Shared action create/use/destroy
>>> ===
>>> Shared action may be reused by some or none flow rules at any given
>>> moment, i.e. shared action resides outside of the context of any flow.
>>> Shared action represent HW resources/objects used for action offloading
>>> implementation.
>>> API for shared action create (see `rte_flow_shared_action_create()`):
>>> - should allocate HW resources and make related initializations required
>>>   for shared action implementation.
>>> - make necessary preparations to maintain shared access to
>>>   the action resources, configuration and state.
>>> API for shared action destroy (see `rte_flow_shared_action_destroy()`)
>>> should release HW resources and make related cleanups required for shared
>>> action implementation.
>>>
>>> In order to share some flow action reuse the handle of type
>>> `struct rte_flow_shared_action` returned by
>>> rte_flow_shared_action_create() as a `conf` field of
>>> `struct rte_flow_action` (see "example" section).
>>>
>>> If some shared action not used by any flow rule all resources allocated
>>> by the shared action can be released by rte_flow_shared_action_destroy()
>>> (see "example" section). The shared action handle passed as argument to
>>> destroy API should not be used any further i.e. result of the usage is
>>> undefined.
>>>
>>> Shared action re-configuration
>>> ===
>>> Shared action behavior defined by its configuration can be updated via
>>> rte_flow_shared_action_update() (see "example" section). The shared
>>> action update operation modifies HW related resources/objects allocated
>>> on the action creation. The number of operations performed by the update
>>> operation should not depend on the number of flows sharing the related
>>> action. On return of shared action update API action behavior should be
>>> according to updated configuration for all flows sharing the action.
>>>
>>> Shared action query
>>> ===
>>> Provide separate API to query shared action state (see
>>> rte_flow_shared_action_update()). Taking a counter as an example: query
>>> returns value aggregating all counter increments across all flow rules
>>> sharing the counter. This API doesn't query shared action configuration
>>> since it is controlled by rte_flow_shared_action_create() and
>>> rte_flow_shared_action_update() APIs and no supposed to change by other
>>> means.
>>>
>>> PMD support
>>> ===
>>> The support of introduced API is pure PMD specific design and
>>> responsibility for each action type (see struct rte_flow_ops).
>>>
>>> testpmd
>>> ===
>>> In order to utilize introduced API testpmd cli may implement following
>>> extension
>>> create/update/destroy/query shared action accordingly
>>>
>>> flow shared_action (port) create {action_id (id)} (action) / end
>>> flow shared_action (port) update (id) (action) / end
>>> flow shared_action (port) destroy action_id (id) {action_id (id) [...]}
>>> flow shared_action (port) query (id)
>>>
>>> testpmd example
>>> ===
>>>
>>> configure rss to queues 1 & 2
>>>
>>>> flow shared_action 0 create action_id 100 rss queues 1 2 end / end
>>>
>>> create flow rule utilizing shared action
>>>
>>>> flow create 0 ingress \
>>>     pattern eth dst is 0c:42:a1:15:fd:ac / ipv6 / tcp / end \
>>>   actions shared 100 / end
>>>
>>> add 2 more queues
>>>
>>>> flow shared_action 0 modify 100 rss queues 1 2 3 4 end / end
>>
>> testpmd is out-of-scope of the patch and it is better to
>> remove the description to avoid unsync if testpmd
>> commands are changed.
> 
> There is still added value is testpmd example demonstrating usage of
> shared action with rte flows. I will update the example to reflect the current
> testpmd syntax for shared action.

Yes and no. IMHO It would be OK for series description etc,
but not OK for the changeset description which will be
kept in the history and will become misleading when
commands are changed. I think that no information is better
than potentially wrong information.

[snip]

>>> diff --git a/lib/librte_ethdev/rte_ethdev_version.map
>> b/lib/librte_ethdev/rte_ethdev_version.map
>>> index c95ef5157a..a8a4821dbb 100644
>>> --- a/lib/librte_ethdev/rte_ethdev_version.map
>>> +++ b/lib/librte_ethdev/rte_ethdev_version.map
>>> @@ -229,6 +229,10 @@ EXPERIMENTAL {
>>>  	# added in 20.11
>>>  	rte_eth_link_speed_to_str;
>>>  	rte_eth_link_to_str;
>>> +	rte_flow_shared_action_create;
>>> +	rte_flow_shared_action_destroy;
>>> +	rte_flow_shared_action_update;
>>> +	rte_flow_shared_action_query;
>>
>> Shouldn't it be alphabetically sorted?
> 
> Query before update?

yes

[snip]

>>> diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
>>> index da8bfa5489..9050adec23 100644
>>> --- a/lib/librte_ethdev/rte_flow.h
>>> +++ b/lib/librte_ethdev/rte_flow.h

[snip]

>>> @@ -3357,6 +3380,150 @@ int
>>>  rte_flow_get_aged_flows(uint16_t port_id, void **contexts,
>>>  			uint32_t nb_contexts, struct rte_flow_error *error);
>>>
>>> +/**
>>> + * Specify shared action configuration
>>> + */
>>> +struct rte_flow_shared_action_conf {
>>> +	/**
>>> +	 * Flow direction for shared action configuration.
>>> +	 *
>>> +	 * Shred action should be valid at least for one flow direction,
>>> +	 * otherwise it is invalid for both ingress and egress rules.
>>> +	 */
>>> +	uint32_t ingress:1;
>>> +	/**< Action valid for rules applied to ingress traffic. */
>>> +	uint32_t egress:1;
>>> +	/**< Action valid for rules applied to egress traffic. */
>>> +};
>>> +
>>> +/**
>>> + * @warning
>>> + * @b EXPERIMENTAL: this API may change without prior notice.
>>> + *
>>> + * Create shared action for reuse in multiple flow rules.
>>> + * The created shared action has single state and configuration
>>> + * across all flow rules using it.
>>> + *
>>> + * @param[in] port_id
>>> + *    The port identifier of the Ethernet device.
>>> + * @param[in] conf
>>> + *   Shared action configuration.
>>> + * @param[in] action
>>> + *   Action configuration for shared action creation.
>>> + * @param[out] error
>>> + *   Perform verbose error reporting if not NULL. PMDs initialize this
>>> + *   structure in case of error only.
>>> + * @return
>>> + *   A valid handle in case of success, NULL otherwise and rte_errno is set
>>> + *   to one of the error codes defined:
>>> + *   - (ENOSYS) if underlying device does not support this functionality.
>>> + *   - (EIO) if underlying device is removed.
>>> + *   - (EINVAL) if *action* invalid.
>>> + *   - (ENOTSUP) if *action* valid but unsupported.
>>
>> ENODEV ?
> 
> Can you elaborate?


ENODEV is returned if port_id is invalid and it should be
documented here if you try to list all return values.


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