From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 61324A0547; Mon, 21 Jun 2021 16:05:49 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 2749F41158; Mon, 21 Jun 2021 16:05:49 +0200 (CEST) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by mails.dpdk.org (Postfix) with ESMTP id 1AB8B40040 for ; Mon, 21 Jun 2021 16:05:46 +0200 (CEST) IronPort-SDR: 6XsNU7CBK92puFOC/r5FNjZqo+wHsqSj86qQyjYjvdEA2djJtaKKiLutat/i6oErKLBjZAyRMw hLTxIAq60GFg== X-IronPort-AV: E=McAfee;i="6200,9189,10021"; a="206891934" X-IronPort-AV: E=Sophos;i="5.83,289,1616482800"; d="scan'208";a="206891934" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2021 07:05:14 -0700 IronPort-SDR: YSNhO/LVkWzasNpmsPWwQmZR8kja3bZOV0q4KfSqXxiCGUfXCrr+x68ZFcUAQq6W3JTkAWtr6e 4xMKIdBGLMWw== X-IronPort-AV: E=Sophos;i="5.83,289,1616482800"; d="scan'208";a="453892043" Received: from fyigit-mobl1.ger.corp.intel.com (HELO [10.213.238.17]) ([10.213.238.17]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2021 07:05:11 -0700 To: "Ananyev, Konstantin" , Thomas Monjalon , "Richardson, Bruce" Cc: =?UTF-8?Q?Morten_Br=c3=b8rup?= , "dev@dpdk.org" , "olivier.matz@6wind.com" , "andrew.rybchenko@oktetlabs.ru" , "honnappa.nagarahalli@arm.com" , "jerinj@marvell.com" , "gakhil@marvell.com" References: <20210614105839.3379790-1-thomas@monjalon.net> <98CBD80474FA8B44BF855DF32C47DC35C6184E@smartserver.smartshare.dk> <2004320.XGyPsaEoyj@thomas> <0bb118ba-2658-a7d7-ad8f-bf27f62849f7@intel.com> From: Ferruh Yigit X-User: ferruhy Message-ID: <43d5d092-73cc-e5a1-5d5d-2e4f9c6c1759@intel.com> Date: Mon, 21 Jun 2021 15:05:08 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH] parray: introduce internal API for dynamic arrays X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 6/21/2021 12:06 PM, Ananyev, Konstantin wrote: > > Hi everyone, > >>>>>> One more thought here - if we are talking about rte_ethdev[] in particular, I think we can: >>>>>> 1. move public function pointers (rx_pkt_burst(), etc.) from rte_ethdev into a separate flat array. >>>>>> We can keep it public to still use inline functions for 'fast' calls rte_eth_rx_burst(), etc. to avoid >>>>>> any regressions. >>>>>> That could still be flat array with max_size specified at application startup. >>>>>> 2. Hide rest of rte_ethdev struct in .c. >>>>>> That will allow us to change the struct itself and the whole rte_ethdev[] table in a way we like >>>>>> (flat array, vector, hash, linked list) without ABI/API breakages. >>>>>> >>>>>> Yes, it would require all PMDs to change prototype for pkt_rx_burst() function >>>>>> (to accept port_id, queue_id instead of queue pointer), but the change is mechanical one. >>>>>> Probably some macro can be provided to simplify it. >>>>>> >>>>> >>>>> We are already planning some tasks for ABI stability for v21.11, I think >>>>> splitting 'struct rte_eth_dev' can be part of that task, it enables hiding more >>>>> internal data. >>>> >>>> Ok, sounds good. >>>> >>>>> >>>>>> The only significant complication I can foresee with implementing that approach - >>>>>> we'll need a an array of 'fast' function pointers per queue, not per device as we have now >>>>>> (to avoid extra indirection for callback implementation). >>>>>> Though as a bonus we'll have ability to use different RX/TX funcions per queue. >>>>>> >>>>> >>>>> What do you think split Rx/Tx callback into its own struct too? >>>>> >>>>> Overall 'rte_eth_dev' can be split into three as: >>>>> 1. rte_eth_dev >>>>> 2. rte_eth_dev_burst >>>>> 3. rte_eth_dev_cb >>>>> >>>>> And we can hide 1 from applications even with the inline functions. >>>> >>>> As discussed off-line, I think: >>>> it is possible. >>>> My absolute preference would be to have just 1/2 (with CB hidden). >>> >>> How can we hide the callbacks since they are used by inline burst functions. >> >> I probably I owe a better explanation to what I meant in first mail. >> Otherwise it sounds confusing. >> I'll try to write a more detailed one in next few days. > > Actually I gave it another thought over weekend, and might be we can > hide rte_eth_dev_cb even in a simpler way. I'd use eth_rx_burst() as > an example, but the same principle applies to other 'fast' functions. > > 1. Needed changes for PMDs rx_pkt_burst(): > a) change function prototype to accept 'uint16_t port_id' and 'uint16_t queue_id', > instead of current 'void *'. > b) Each PMD rx_pkt_burst() will have to call rte_eth_rx_epilog() function at return. > This inline function will do all CB calls for that queue. > > To be more specific, let say we have some PMD: xyz with RX function: > > uint16_t > xyz_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts) > { > struct xyz_rx_queue *rxq = rx_queue; > uint16_t nb_rx = 0; > > /* do actual stuff here */ > .... > return nb_rx; > } > > It will be transformed to: > > uint16_t > xyz_recv_pkts(uint16_t port_id, uint16_t queue_id, struct rte_mbuf **rx_pkts, uint16_t nb_pkts) > { > struct xyz_rx_queue *rxq; > uint16_t nb_rx; > > rxq = _rte_eth_rx_prolog(port_id, queue_id); > if (rxq == NULL) > return 0; > nb_rx = _xyz_real_recv_pkts(rxq, rx_pkts, nb_pkts); > return _rte_eth_rx_epilog(port_id, queue_id, rx_pkts, nb_pkts); > } > > And somewhere in ethdev_private.h: > > static inline void * > _rte_eth_rx_prolog(uint16_t port_id, uint16_t queue_id); > { > struct rte_eth_dev *dev = &rte_eth_devices[port_id]; > > #ifdef RTE_ETHDEV_DEBUG_RX > RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, NULL); > RTE_FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, NULL); > > if (queue_id >= dev->data->nb_rx_queues) { > RTE_ETHDEV_LOG(ERR, "Invalid RX queue_id=%u\n", queue_id); > return NULL; > } > #endif > return dev->data->rx_queues[queue_id]; > } > > static inline uint16_t > _rte_eth_rx_epilog(uint16_t port_id, uint16_t queue_id, struct rte_mbuf **rx_pkts, const uint16_t nb_pkts); > { > struct rte_eth_dev *dev = &rte_eth_devices[port_id]; > > #ifdef RTE_ETHDEV_RXTX_CALLBACKS > struct rte_eth_rxtx_callback *cb; > > /* __ATOMIC_RELEASE memory order was used when the > * call back was inserted into the list. > * Since there is a clear dependency between loading > * cb and cb->fn/cb->next, __ATOMIC_ACQUIRE memory order is > * not required. > */ > cb = __atomic_load_n(&dev->post_rx_burst_cbs[queue_id], > __ATOMIC_RELAXED); > > if (unlikely(cb != NULL)) { > do { > nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx, > nb_pkts, cb->param); > cb = cb->next; > } while (cb != NULL); > } > #endif > > rte_ethdev_trace_rx_burst(port_id, queue_id, (void **)rx_pkts, nb_rx); > return nb_rx; > } > > Now, as you said above, in rte_ethdev.h we will keep only a flat array > with pointers to 'fast' functions: > struct { > eth_rx_burst_t rx_pkt_burst > eth_tx_burst_t tx_pkt_burst; > eth_tx_prep_t tx_pkt_prepare; > ..... > } rte_eth_dev_burst[]; > > And rte_eth_rx_burst() will look like: > > static inline uint16_t > rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id, > struct rte_mbuf **rx_pkts, const uint16_t nb_pkts) > { > if (port_id >= RTE_MAX_ETHPORTS) > return 0; > return rte_eth_dev_burst[port_id](port_id, queue_id, rx_pkts, nb_pkts); > } > > Yes, it will require changes in *all* PMDs, but as I said before the changes will be a mechanic ones. > I did not like the idea to push to calling Rx/TX callbacks responsibility to the drivers, I think it should be in the ethdev layer. What about making 'rte_eth_rx_epilog' an API and call from 'rte_eth_rx_burst()', which will add another function call for Rx/Tx callback but shouldn't affect the Rx/Tx burst.