From patchwork Sat Sep 23 20:23:09 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Scheurich X-Patchwork-Id: 29131 Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id E07631AEF5; Sat, 23 Sep 2017 22:23:11 +0200 (CEST) Received: from sessmg23.ericsson.net (sessmg23.ericsson.net [193.180.251.45]) by dpdk.org (Postfix) with ESMTP id 84D301AEEE for ; Sat, 23 Sep 2017 22:23:10 +0200 (CEST) X-AuditID: c1b4fb2d-a4dff700000019be-70-59c6c2ae8619 Received: from ESESSHC003.ericsson.se (Unknown_Domain [153.88.183.27]) by sessmg23.ericsson.net (Symantec Mail Security) with SMTP id 35.17.06590.EA2C6C95; Sat, 23 Sep 2017 22:23:10 +0200 (CEST) Received: from ESESSMB107.ericsson.se ([169.254.7.166]) by ESESSHC003.ericsson.se ([153.88.183.27]) with mapi id 14.03.0352.000; Sat, 23 Sep 2017 22:23:09 +0200 From: Jan Scheurich To: "'dev@dpdk.org'" Thread-Topic: [PATCH v2] vhost: Expose virtio interrupt need on rte_vhost API Thread-Index: AdM0qYHOsmG+F+M6Q46FCjtwgqhaXQ== Date: Sat, 23 Sep 2017 20:23:09 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [153.88.183.150] MIME-Version: 1.0 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrLLMWRmVeSWpSXmKPExsUyM2K7tO66Q8ciDU4u47V492k7kwOjx68F S1kDGKO4bFJSczLLUov07RK4Mu5sOsNecEu8onvxStYGxltCXYwcHBICJhJth526GLk4hASO MErc/z2LCcJZwijR03qEFaSITcBAYvZuhy5GTg4RAWWJWce2s4HYwgIeEo8PPGCCiPtKdD7d ygJh60lMnzWLGcRmEVCVmLH9EVgNL1DN8u8fwOKMAmIS30+tAYszC4hL3HoyH8yWEBCQWLLn PDOELSrx8vE/VghbSWLF9kuMEPU6Egt2f2KDsLUlli18zQwxX1Di5MwnLBMYhWYhGTsLScss JC2zkLQsYGRZxShanFpcnJtuZKyXWpSZXFycn6eXl1qyiREYyAe3/Nbdwbj6teMhRgEORiUe 3hnbjkUKsSaWFVfmHmKU4GBWEuG13gkU4k1JrKxKLcqPLyrNSS0+xCjNwaIkzuuw70KEkEB6 YklqdmpqQWoRTJaJg1OqgdEidr35W/kQo1/5V9SWmL57WLdvtn3V3r1n6udO+eL7qGYNv65Z 7tvfU/zV3rxR46tmep8RkTw/tuFSesLNzuWys2O17BimdnyMCqiomCd791JNjrZm14K5nW8b NhwrbPs889eXHYsqV51NPj3r/c3Hh8pFN9j9MkrO1/ifLRqaFbJ7esXivTJKLMUZiYZazEXF iQA8xRw5YAIAAA== Subject: [dpdk-dev] [PATCH v2] vhost: Expose virtio interrupt need on rte_vhost API 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" Performance tests with the OVS DPDK datapath have shown that the tx throughput over a vhostuser port into a VM with an interrupt-based virtio driver is limited by the overhead incurred by virtio interrupts. The OVS PMD spends up to 30% of its cycles in system calls kicking the eventfd. Also the core running the vCPU is heavily loaded with generating the virtio interrupts in KVM on the host and handling these interrupts in the virtio-net driver in the guest. This limits the throughput to about 500-700 Kpps with a single vCPU. OVS is trying to address this issue by batching packets to a vhostuser port for some time to limit the virtio interrupt frequency. With a 50 us batching period we have measured an iperf3 throughput increase by 15% and a PMD utilization decrease from 45% to 30%. On the other hand, guests using virtio PMDs do not profit from time-based tx batching. Instead they experience a 2-3% performance penalty and an average latency increase of 30-40 us. OVS therefore intends to apply time-based tx batching only for vhostuser tx queues that need to trigger virtio interrupts. Today this information is hidden inside the rte_vhost library and not accessible to users of the API. This patch adds a function to the API to query it. Signed-off-by: Jan Scheurich --- v1 -> v2: Fixed too long commit lines Fixed white-space errors and warnings lib/librte_vhost/rte_vhost.h | 12 ++++++++++++ lib/librte_vhost/vhost.c | 19 +++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h index 8c974eb..d62338b 100644 --- a/lib/librte_vhost/rte_vhost.h +++ b/lib/librte_vhost/rte_vhost.h @@ -444,6 +444,18 @@ int rte_vhost_get_vhost_vring(int vid, uint16_t vring_idx, */ uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid); +/** + * Does the virtio driver request interrupts for a vhost tx queue? + * + * @param vid + * vhost device ID + * @param qid + * virtio queue index in mq case + * @return + * 1 if true, 0 if false + */ +int rte_vhost_tx_interrupt_requested(int vid, uint16_t qid); + #ifdef __cplusplus } #endif diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c index 0b6aa1c..c6e636e 100644 --- a/lib/librte_vhost/vhost.c +++ b/lib/librte_vhost/vhost.c @@ -503,3 +503,22 @@ struct virtio_net * return *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx; } + +int rte_vhost_tx_interrupt_requested(int vid, uint16_t qid) +{ + struct virtio_net *dev; + struct vhost_virtqueue *vq; + + dev = get_device(vid); + if (dev == NULL) + return 0; + + vq = dev->virtqueue[qid]; + if (vq == NULL) + return 0; + + if (unlikely(vq->enabled == 0 || vq->avail == NULL)) + return 0; + + return !(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT); +}