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From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: "Yigit, Ferruh" <ferruh.yigit@intel.com>,
	Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
	Lijun Ou <oulijun@huawei.com>,
	"thomas@monjalon.net" <thomas@monjalon.net>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"linuxarm@openeuler.org" <linuxarm@openeuler.org>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	David Marchand <david.marchand@redhat.com>,
	Ray Kinsella <mdr@ashroe.eu>, Luca Boccassi <bluca@debian.org>,
	Ori Kam <orika@nvidia.com>
Subject: Re: [dpdk-dev] [PATCH] ethdev: add queue state when retrieve queue information
Date: Tue, 23 Mar 2021 11:07:48 +0000	[thread overview]
Message-ID: <DM6PR11MB44910B520AF2AC9488A2DE179A649@DM6PR11MB4491.namprd11.prod.outlook.com> (raw)
In-Reply-To: <4fa64451-b647-c946-733e-a95297cdfa4a@intel.com>




> >>>>>>>>
> >>>>>>>> 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 <fengchengwen@huawei.com>
> >>>>>>>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> >>>>>>>
> >>>>>>> <...>
> >>>>>>>
> >>>>>>>> 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.
> >
> > As alternate thought - introduce new API function,
> > something like:
> > int rte_eth_get_rxq_state(portid, queue_id);
> > Then rte_eth_dev_is_rx_hairpin_queue() probably can be deprecated
> > in favour of this new one.
> >
> >
> 
> The 'rte_eth_dev_is_rx_hairpin_queue()' is internal function, and it is not
> visible to the application, it should be OK to keep it.

What I am saying - we well have get-state() - PMDs can use the new one
instead of  rte_eth_dev_is_rx_hairpin_queue().
Or rte_eth_dev_is_rx_hairpin_queue() can be just a wrapper around get_rxq_state().

> 
> But 'STATE_HAIRPIN' should be kept internal, or should be available to the
> application?
> 
> The actual need is to know the start/stop state of the queue. That is for app to
> decide if 'rte_eth_tx_done_cleanup()' can be done or not an a queue:
> https://patches.dpdk.org/project/dpdk/patch/1614938252-62955-1-git-send-email-oulijun@huawei.com/

If we don't expose STATE_HAIRPIN what state we will report 
for hairpin queue back to the user?
Either STARTED or STOPPED are both invalid and misleading.
I  think we have to report all 3 supported states back to the user.

> 
> And normally I also prefer APIs with simple & clear responsibility, but this one
> seems very related to the existing '_queue_info_get()' ones, so I am fine with
> both options.


  parent reply	other threads:[~2021-03-23 11:08 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 12:25 Lijun Ou
2021-03-22  9:22 ` Ferruh Yigit
2021-03-22  9:38   ` Kinsella, Ray
2021-03-22  9:39   ` oulijun
2021-03-22 14:49   ` Andrew Rybchenko
2021-03-22 15:45     ` Ananyev, Konstantin
2021-03-22 16:02       ` Andrew Rybchenko
2021-03-22 16:53         ` Ananyev, Konstantin
2021-03-22 17:07           ` Andrew Rybchenko
2021-03-22 18:53             ` Ananyev, Konstantin
2021-03-23 10:13               ` Ferruh Yigit
2021-03-23 10:19                 ` Ferruh Yigit
2021-03-23 11:07                 ` Ananyev, Konstantin [this message]
2021-03-25 10:01       ` oulijun
2021-03-25 10:18         ` Ananyev, Konstantin
2021-03-25 11:09 ` [dpdk-dev] [PATCH V2] " Lijun Ou
2021-04-06  0:49   ` oulijun
2021-04-06  1:55     ` Stephen Hemminger
2021-04-14 10:09       ` Ferruh Yigit
2021-04-06 14:02   ` Ananyev, Konstantin
2021-04-14 10:40     ` Ferruh Yigit
2021-04-14 10:56       ` Ananyev, Konstantin
2021-04-15  2:40   ` [dpdk-dev] [PATCH V3] " Lijun Ou
2021-04-15 12:33     ` Ferruh Yigit
2021-04-15 12:36       ` Thomas Monjalon
2021-04-15 12:45         ` Ferruh Yigit
2021-04-15 13:34           ` Thomas Monjalon
2021-04-16  0:58           ` [dpdk-dev] [Linuxarm] " oulijun
2021-04-16  7:31             ` Ferruh Yigit
2021-04-16  8:46     ` [dpdk-dev] [PATCH V4] " Lijun Ou
2021-04-16  8:58       ` Thomas Monjalon
2021-04-16  9:41         ` Ferruh Yigit
2021-04-16  9:57           ` Thomas Monjalon
2021-04-23 11:08             ` Kinsella, Ray
2021-04-25 16:42               ` Thomas Monjalon
2021-04-26  9:48                 ` Kinsella, Ray
2021-04-16  9:55         ` oulijun
2021-04-16  9:19       ` Ananyev, Konstantin
2021-04-17  3:09       ` [dpdk-dev] [PATCH V5] " Lijun Ou
2021-04-17 22:00         ` Ferruh Yigit
2021-04-19  1:39           ` oulijun
2021-04-19  2:04           ` oulijun
2021-04-19  2:03         ` [dpdk-dev] [PATCH V6] " Lijun Ou
2021-04-19  8:41           ` Thomas Monjalon
2021-04-19  8:58             ` oulijun
2021-04-19  8:57           ` [dpdk-dev] [PATCH v7] " Lijun Ou
2021-04-19  9:03             ` Thomas Monjalon
2021-04-19 10:48               ` Ferruh Yigit
2021-04-23 11:17         ` [dpdk-dev] [PATCH V5] " Kinsella, Ray
2021-04-23 11:26           ` Ananyev, Konstantin
2021-04-23 15:43             ` Kinsella, Ray

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