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[193.106.246.138]) by smtp.gmail.com with ESMTPSA id e8sm765685lja.3.2020.04.08.01.30.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2020 01:30:00 -0700 (PDT) From: Michal Krawczyk To: dev@dpdk.org Cc: mw@semihalf.com, mba@semihalf.com, gtzalik@amazon.com, evgenys@amazon.com, igorch@amazon.com, ferruh.yigit@intel.com, arybchenko@solarflare.com, Michal Krawczyk Date: Wed, 8 Apr 2020 10:29:19 +0200 Message-Id: <20200408082921.31000-29-mk@semihalf.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200408082921.31000-1-mk@semihalf.com> References: <20200408082921.31000-1-mk@semihalf.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH v3 28/30] net/ena: reuse 0 length Rx descriptor X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 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" Some ENA devices can pass to the driver descriptor with length 0. To avoid extra allocation, the descriptor can be reused by simply putting it back to the device. Signed-off-by: Michal Krawczyk Reviewed-by: Igor Chauskin Reviewed-by: Guy Tzalik --- v2: * Compare rc (error code) to 0 value explicitely v3: * Update release notes doc/guides/rel_notes/release_20_05.rst | 1 + drivers/net/ena/ena_ethdev.c | 75 ++++++++++++++++++++------ 2 files changed, 61 insertions(+), 15 deletions(-) diff --git a/doc/guides/rel_notes/release_20_05.rst b/doc/guides/rel_notes/release_20_05.rst index e6b2f1b972..89a48a1ff8 100644 --- a/doc/guides/rel_notes/release_20_05.rst +++ b/doc/guides/rel_notes/release_20_05.rst @@ -85,6 +85,7 @@ New Features * Added support for large LLQ (Low-latency queue) headers. * Added Tx drops as new extended driver statistic. * Added support for accelerated LLQ mode. + * Handling of the 0 length descriptors on the Rx path. Removed Items diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c index 1a7cc686f5..156a3e441b 100644 --- a/drivers/net/ena/ena_ethdev.c +++ b/drivers/net/ena/ena_ethdev.c @@ -195,6 +195,8 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring, uint8_t offset); static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts); +static int ena_add_single_rx_desc(struct ena_com_io_sq *io_sq, + struct rte_mbuf *mbuf, uint16_t id); static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count); static void ena_init_rings(struct ena_adapter *adapter, bool disable_meta_caching); @@ -1414,6 +1416,24 @@ static int ena_rx_queue_setup(struct rte_eth_dev *dev, return 0; } +static int ena_add_single_rx_desc(struct ena_com_io_sq *io_sq, + struct rte_mbuf *mbuf, uint16_t id) +{ + struct ena_com_buf ebuf; + int rc; + + /* prepare physical address for DMA transaction */ + ebuf.paddr = mbuf->buf_iova + RTE_PKTMBUF_HEADROOM; + ebuf.len = mbuf->buf_len - RTE_PKTMBUF_HEADROOM; + + /* pass resource to device */ + rc = ena_com_add_single_rx_desc(io_sq, &ebuf, id); + if (unlikely(rc != 0)) + PMD_DRV_LOG(WARNING, "failed adding rx desc\n"); + + return rc; +} + static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count) { unsigned int i; @@ -1441,7 +1461,6 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count) for (i = 0; i < count; i++) { struct rte_mbuf *mbuf = mbufs[i]; - struct ena_com_buf ebuf; struct ena_rx_buffer *rx_info; if (likely((i + 4) < count)) @@ -1454,16 +1473,10 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count) rx_info = &rxq->rx_buffer_info[req_id]; - /* prepare physical address for DMA transaction */ - ebuf.paddr = mbuf->buf_iova + RTE_PKTMBUF_HEADROOM; - ebuf.len = mbuf->buf_len - RTE_PKTMBUF_HEADROOM; - /* pass resource to device */ - rc = ena_com_add_single_rx_desc(rxq->ena_com_io_sq, - &ebuf, req_id); - if (unlikely(rc)) { - PMD_DRV_LOG(WARNING, "failed adding rx desc\n"); + rc = ena_add_single_rx_desc(rxq->ena_com_io_sq, mbuf, req_id); + if (unlikely(rc != 0)) break; - } + rx_info->mbuf = mbuf; next_to_use = ENA_IDX_NEXT_MASKED(next_to_use, rxq->size_mask); } @@ -2079,6 +2092,7 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring, struct rte_mbuf *mbuf; struct rte_mbuf *mbuf_head; struct ena_rx_buffer *rx_info; + int rc; uint16_t ntc, len, req_id, buf = 0; if (unlikely(descs == 0)) @@ -2121,13 +2135,44 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring, rx_info = &rx_ring->rx_buffer_info[req_id]; RTE_ASSERT(rx_info->mbuf != NULL); - /* Create an mbuf chain. */ - mbuf->next = rx_info->mbuf; - mbuf = mbuf->next; + if (unlikely(len == 0)) { + /* + * Some devices can pass descriptor with the length 0. + * To avoid confusion, the PMD is simply putting the + * descriptor back, as it was never used. We'll avoid + * mbuf allocation that way. + */ + rc = ena_add_single_rx_desc(rx_ring->ena_com_io_sq, + rx_info->mbuf, req_id); + if (unlikely(rc != 0)) { + /* Free the mbuf in case of an error. */ + rte_mbuf_raw_free(rx_info->mbuf); + } else { + /* + * If there was no error, just exit the loop as + * 0 length descriptor is always the last one. + */ + break; + } + } else { + /* Create an mbuf chain. */ + mbuf->next = rx_info->mbuf; + mbuf = mbuf->next; - ena_init_rx_mbuf(mbuf, len); - mbuf_head->pkt_len += len; + ena_init_rx_mbuf(mbuf, len); + mbuf_head->pkt_len += len; + } + /* + * Mark the descriptor as depleted and perform necessary + * cleanup. + * This code will execute in two cases: + * 1. Descriptor len was greater than 0 - normal situation. + * 2. Descriptor len was 0 and we failed to add the descriptor + * to the device. In that situation, we should try to add + * the mbuf again in the populate routine and mark the + * descriptor as used up by the device. + */ rx_info->mbuf = NULL; rx_ring->empty_rx_reqs[ntc] = req_id; ntc = ENA_IDX_NEXT_MASKED(ntc, rx_ring->size_mask); -- 2.20.1