On 3/22/21 7:53 PM, Ananyev, Konstantin wrote: > > >> -----Original Message----- >> From: Andrew Rybchenko <[email protected]> >> Sent: Monday, March 22, 2021 4:02 PM >> To: Ananyev, Konstantin <[email protected]>; Yigit, Ferruh >> <[email protected]>; Lijun Ou <[email protected]>; >> [email protected] >> Cc: [email protected]; [email protected]; Andrew Rybchenko >> <[email protected]>; David Marchand >> <[email protected]>; Ray Kinsella <[email protected]>; Luca Boccassi >> <[email protected]> >> Subject: Re: [dpdk-dev] [PATCH] ethdev: add queue state when retrieve queue >> information >> >> On 3/22/21 6:45 PM, Ananyev, Konstantin wrote: >>> >>> >>>> -----Original Message----- >>>> From: dev <[email protected]> On Behalf Of Andrew Rybchenko >>>> Sent: Monday, March 22, 2021 2:49 PM >>>> To: Yigit, Ferruh <[email protected]>; Lijun Ou <[email protected]>; >>>> [email protected] >>>> Cc: [email protected]; [email protected]; Andrew Rybchenko >>>> <[email protected]>; David Marchand >>>> <[email protected]>; Ray Kinsella <[email protected]>; Luca Boccassi >>>> <[email protected]> >>>> Subject: Re: [dpdk-dev] [PATCH] ethdev: add queue state when retrieve >>>> queue information >>>> >>>> On 3/22/21 12:22 PM, Ferruh Yigit wrote: >>>>> On 3/18/2021 12:25 PM, Lijun Ou wrote: >>>>>> Currently, upper-layer application could get queue state only >>>>>> through pointers such as dev->data->tx_queue_state[queue_id], >>>>>> this is not the recommended way to access it. So this patch >>>>>> add get queue state when call rte_eth_rx_queue_info_get and >>>>>> rte_eth_tx_queue_info_get API. >>>>>> >>>>>> Note: The hairpin queue is not supported with above >>>>>> rte_eth_*x_queue_info_get, so the queue state could be >>>>>> RTE_ETH_QUEUE_STATE_STARTED or RTE_ETH_QUEUE_STATE_STOPPED. >>>>>> Note: After add queue_state field, the 'struct rte_eth_rxq_info' size >>>>>> remains 128B, and the 'struct rte_eth_txq_info' size remains 64B, so >>>>>> it could be ABI compatible. >>>>>> >>>>>> Signed-off-by: Chengwen Feng <[email protected]> >>>>>> Signed-off-by: Lijun Ou <[email protected]> >>>>> >>>>> <...> >>>>> >>>>>> diff --git a/lib/librte_ethdev/rte_ethdev.h >>>>>> b/lib/librte_ethdev/rte_ethdev.h >>>>>> index efda313..3b83c5a 100644 >>>>>> --- a/lib/librte_ethdev/rte_ethdev.h >>>>>> +++ b/lib/librte_ethdev/rte_ethdev.h >>>>>> @@ -1591,6 +1591,8 @@ struct rte_eth_rxq_info { >>>>>> uint8_t scattered_rx; /**< scattered packets RX supported. */ >>>>>> uint16_t nb_desc; /**< configured number of RXDs. */ >>>>>> uint16_t rx_buf_size; /**< hardware receive buffer size. */ >>>>>> + /**< Queues state: STARTED(1) / STOPPED(0). */ >>>>>> + uint8_t queue_state; >>>>>> } __rte_cache_min_aligned; >>>>>> /** >>>>>> @@ -1600,6 +1602,8 @@ struct rte_eth_rxq_info { >>>>>> struct rte_eth_txq_info { >>>>>> struct rte_eth_txconf conf; /**< queue config parameters. */ >>>>>> uint16_t nb_desc; /**< configured number of TXDs. */ >>>>>> + /**< Queues state: STARTED(1) / STOPPED(0). */ >>>>>> + uint8_t queue_state; >>>>>> } __rte_cache_min_aligned; >>>>>> /* Generic Burst mode flag definition, values can be ORed. */ >>>>>> >>>>> >>>>> This is causing an ABI warning [1], but I guess it is safe since the >>>>> size of the struct is not changing (cache align). Adding a few more >>>>> people to comment. >>>>> >>>>> >>>>> [1] >>>>> https://travis-ci.com/github/ovsrobot/dpdk/builds/220497651 >>>> >>>> Frankly speaking I dislike addition of queue_state as uint8_t. >>>> IMHO it should be either 'bool started' or enum to support more >>>> states in the future if we need. >>> >>> I think we already have set of defines for it: >>> lib/librte_ethdev/rte_ethdev_driver.h:925:#define >>> RTE_ETH_QUEUE_STATE_STOPPED 0 >>> lib/librte_ethdev/rte_ethdev_driver.h:926:#define >>> RTE_ETH_QUEUE_STATE_STARTED 1 >>> lib/librte_ethdev/rte_ethdev_driver.h:927:#define >>> RTE_ETH_QUEUE_STATE_HAIRPIN 2 >>> >>> If we want to publish it, then might be enough just move these macros to >>> rte_ethdev.h or so. >>> >>> About uint8_t vs enum - yes, in principle enum would be a bit nicer, >>> but right now rte_eth_dev_data.(rx|tx)_queue_state[] itself is an array of >>> uint8_t. >>> So probably not much point to waste extra 3B in rte_eth_(rxq|txq)_info. >>> Unless in future will want to change it in struct rte_eth_dev_data too >>> (or even hide it inside dev private queue data). >> >> I forgot about hairpin and bitmask... If so, I think it is >> sufficient to fix absolutely misleading comment, say >> that it is a bit mask and think about removal of >> RTE_ETH_QUEUE_STATE_STOPPED (since it could be >> stopped+hairpin). May be consider to use uin16_t, >> since 8 bit is really small bitmask. It still fits in >> available hole. > > Hmm, as I can read the code - hairpin queue can't be started/stopped by SW, > and each of the states (stopped/started/hairpin) is mutually exclusive. > Is that not what was intended when hairpin queues were introduced? >
Thanks, yes, you're right. My memory lies to me. If queue state is not a bit mask, it should be an enum from API point of view. Rx/Tx queue info structures are control path. I see no point to save bits here. Clear API is more important on control path. The only reason here to use uint8_t is to avoid ABI breakage. I can't judge if it is critical to wait or not.
