[ovs-dev] [PATCH V2 11/19] dpif-netdev: Read hw stats during flow_dump_next() call
Eli Britstein
elibr at mellanox.com
Fri Dec 6 16:29:13 UTC 2019
On 12/6/2019 6:04 PM, Ilya Maximets wrote:
> On 04.12.2019 21:23, Eli Britstein wrote:
>> On 12/4/2019 8:58 PM, Ilya Maximets wrote:
>>> On 04.12.2019 18:15, Eli Britstein wrote:
>>>> On 12/4/2019 5:58 PM, Ilya Maximets wrote:
>>>>> On 04.12.2019 16:41, Eli Britstein wrote:
>>>>>> On 12/4/2019 5:16 PM, Ilya Maximets wrote:
>>>>>>> On 02.12.2019 09:41, Eli Britstein wrote:
>>>>>>>> From: Ophir Munk<ophirmu at mellanox.com>
>>>>>>>>
>>>>>>>> Use netdev dump flow next API in order to update the statistics of fully
>>>>>>>> offloaded flows.
>>>>>>>>
>>>>>>>> Co-authored-by: Eli Britstein<elibr at mellanox.com>
>>>>>>>> Signed-off-by: Ophir Munk<ophirmu at mellanox.com>
>>>>>>>> Reviewed-by: Oz Shlomo<ozsh at mellanox.com>
>>>>>>>> Signed-off-by: Eli Britstein<elibr at mellanox.com>
>>>>>>>> ---
>>>>>>>> lib/dpif-netdev.c | 42 ++++++++++++++++++++++++++++++++++++++++--
>>>>>>>> 1 file changed, 40 insertions(+), 2 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
>>>>>>>> index 5142bad1d..bfeb1e7b0 100644
>>>>>>>> --- a/lib/dpif-netdev.c
>>>>>>>> +++ b/lib/dpif-netdev.c
>>>>>>>> @@ -527,6 +527,7 @@ struct dp_netdev_flow {
>>>>>>>>
>>>>>>>> bool dead;
>>>>>>>> uint32_t mark; /* Unique flow mark assigned to a flow */
>>>>>>>> + bool actions_offloaded; /* true if flow is fully offloaded */
>>>>>>>>
>>>>>>>> /* Statistics. */
>>>>>>>> struct dp_netdev_flow_stats stats;
>>>>>>>> @@ -2410,6 +2411,7 @@ dp_netdev_flow_offload_put(struct dp_flow_offload_item *offload)
>>>>>>>> }
>>>>>>>> }
>>>>>>>> info.flow_mark = mark;
>>>>>>>> + info.actions_offloaded = &flow->actions_offloaded;
>>>>>>>>
>>>>>>>> ovs_mutex_lock(&pmd->dp->port_mutex);
>>>>>>>> port = dp_netdev_lookup_port(pmd->dp, in_port);
>>>>>>>> @@ -3073,8 +3075,8 @@ dp_netdev_flow_to_dpif_flow(const struct dp_netdev_flow *netdev_flow,
>>>>>>>> flow->pmd_id = netdev_flow->pmd_id;
>>>>>>>> get_dpif_flow_stats(netdev_flow, &flow->stats);
>>>>>>>>
>>>>>>>> - flow->attrs.offloaded = false;
>>>>>>>> - flow->attrs.dp_layer = "ovs";
>>>>>>>> + flow->attrs.offloaded = netdev_flow->actions_offloaded;
>>>>>>>> + flow->attrs.dp_layer = flow->attrs.offloaded ? "in_hw" : "ovs";
>>>>>>>> }
>>>>>>>>
>>>>>>>> static int
>>>>>>>> @@ -3244,6 +3246,7 @@ dp_netdev_flow_add(struct dp_netdev_pmd_thread *pmd,
>>>>>>>> flow->dead = false;
>>>>>>>> flow->batch = NULL;
>>>>>>>> flow->mark = INVALID_FLOW_MARK;
>>>>>>>> + flow->actions_offloaded = false;
>>>>>>>> *CONST_CAST(unsigned *, &flow->pmd_id) = pmd->core_id;
>>>>>>>> *CONST_CAST(struct flow *, &flow->flow) = match->flow;
>>>>>>>> *CONST_CAST(ovs_u128 *, &flow->ufid) = *ufid;
>>>>>>>> @@ -3598,6 +3601,37 @@ dpif_netdev_flow_dump_thread_destroy(struct dpif_flow_dump_thread *thread_)
>>>>>>>> free(thread);
>>>>>>>> }
>>>>>>>>
>>>>>>>> +static int
>>>>>>>> +dpif_netdev_offload_used(struct dp_netdev_flow *netdev_flow,
>>>>>>>> + struct dp_netdev_pmd_thread *pmd)
>>>>>>>> +{
>>>>>>>> + struct netdev_flow_dump netdev_dump;
>>>>>>>> + struct dpif_flow_stats stats;
>>>>>>>> + ovs_u128 ufid;
>>>>>>>> + bool has_next;
>>>>>>>> +
>>>>>>>> + netdev_dump.port = netdev_flow->flow.in_port.odp_port;
>>>>>>>> + netdev_dump.netdev = netdev_ports_get(netdev_dump.port, pmd->dp->class);
>>>>>>>> + if (!netdev_dump.netdev) {
>>>>>>>> + return -1;
>>>>>>>> + }
>>>>>>>> + /* get offloaded stats */
>>>>>>>> + ufid = netdev_flow->mega_ufid;
>>>>>>>> + has_next = netdev_flow_dump_next(&netdev_dump, NULL, NULL, &stats, NULL,
>>>>>>>> + &ufid, NULL, NULL);
>>>>>>> This will not work with linux TC flow API.
>>>>>>> You should not create 'netdev_flow_dump' by yourself, it must be created
>>>>>>> by the netdev_ports_flow_dump_create().
>>>>>> It is different in linux TC.
>>>>>>
>>>>>> In kernel, dump request is done in dump_create API, for each device
>>>>>> (using netdev_ports_flow_dump_create).
>>>>>>
>>>>>> In user space we don't query the driver at all but the flows are looped
>>>>>> by their PMD. We don't need any specific netdev action.
>>>>>>
>>>>>> In kernel, dump next handle a chunk of replies from the kernel, without
>>>>>> any known order or properties - neither by device nor by any other
>>>>>> property, and the next handles the multi-threaded aspect of the dump.
>>>>>>
>>>>>> In user space the flows are known by the PMD looping, and the
>>>>>> multi-threaded scheme is handled by the PMD thread, so this is also
>>>>>> different.
>>>>>>
>>>>>> In kernel, the dump_next gets the flows from the kernel, and deduct the
>>>>>> UFID for each one. In user space we get the UFID as known, and deduct
>>>>>> the rte_flow, also different.
>>>>> I don't see the limitation that will not allow you to implement the
>>>>> same thing for netdev-offload-dpdk. It knows all the flows and ufids
>>>>> and you just need to iterate over them. You may also dump flows
>>>>> directly from the HW because you can request them.
>>>> Correct me if I'm wrong, but DPDK doesn't provide an API to "request" HW
>>>> flows.
>>> At least, you could check if your flow is still in HW with rte_flow_query().
>> This is exactly what is done.
>>> Hopefully, functionality of rte_flow_query() will be expanded to dump flows
>>> themselves or some new API will appear.
>>>
>>>>> There is almost same thing implemented for datapath flow dumps. Just
>>>>> look at the API:
>>>>> dpif_netdev_flow_dump_create,
>>>>> dpif_netdev_flow_dump_destroy,
>>>>> dpif_netdev_flow_dump_thread_create,
>>>>> dpif_netdev_flow_dump_thread_destroy,
>>>>> dpif_netdev_flow_dump_next
>>>>>
>>>>> And dpif-netdev fully implements it regardless of fact that this could
>>>>> be done much easier in userspace datapath.
>>>> Yes, those functions are implemented, but the scheme of querying the
>>>> flows is different, as in my comments above.
>>> dpif-netdev follows the dpif-provider API. It doesn't matter how exactly
>>> it implements this API. The key point is that caller doesn't need to
>>> know which dpif it uses.
>>>
>>> The same with netdev-offload API. Linux TC offload-provider implements
>>> the API and DPDK offload-provider must implement the same API.
>>> In this case datapath will not need to know from which offload-provider
>>> it dumps these flows.
>>>
>>> netdev-offload-dpdk could has all the information it needs to implement
>>> the API properly. If needed you may additionally store all required data
>>> about flows.
>>>
>>>> So, I will implement flow_get API instead, and fill only the stats,
>>>> queried from the HW.
>>> That doesn't make any sense.
>> In dpif_netdev_flow_dump_next the flow and its properties are known from
>> pmd->flow_table. The only missing info is the statistics, in case the
>> flow is offloaded. I want to call netdev_flow_get and implement it in
>> netdev-offload-dpdk to query the statistics, to complete the information
>> about the flow.
>>
>> Could you please elaborate why doesn't it make sense?
> Will you provide implementation of netdev_flow_get() for netdev-offload-tc?
It's already implemented for TC.
>
>
>>>>>> The code in this commit is not relevant for linux TC, not breaking it,
>>>>>> so I don't see "this will will not work with linux TC" issue.
>>>>> This code should work if you'll add netdev-linux port to userspace
>>>>> datapath and linux TC offloading API will be initialized for it.
>>>>> Current implementation will not work.
>>>> If so, it is currently broken as is. The current dpif-netdev.c code
>>>> doesn't read any HW statistics before my patch.
>>> Right now it's not implemented. With your implementation OVS will
>>> crash on attempt to dump linux TC flows from the userspace datapath.
>> Ack
>>
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