From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Coquelin Subject: Re: [PATCH v5 5/6] vhost: batch update used ring Date: Thu, 15 Sep 2016 18:38:06 +0200 Message-ID: <52dba6dc-ca0d-1aeb-cf18-89470450a183@redhat.com> References: <1471319402-112998-1-git-send-email-zhihong.wang@intel.com> <1473392368-84903-1-git-send-email-zhihong.wang@intel.com> <1473392368-84903-6-git-send-email-zhihong.wang@intel.com> <473ef253-86bf-9a7a-d028-21c27690a421@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E70FB6A@SHSMSX103.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "yuanhan.liu@linux.intel.com" , "thomas.monjalon@6wind.com" To: "Wang, Zhihong" , "dev@dpdk.org" Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 9EF3E374F for ; Thu, 15 Sep 2016 18:38:11 +0200 (CEST) In-Reply-To: <8F6C2BD409508844A0EFC19955BE09414E70FB6A@SHSMSX103.ccr.corp.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 09/14/2016 10:43 AM, Wang, Zhihong wrote: > > >> -----Original Message----- >> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] >> Sent: Monday, September 12, 2016 11:46 PM >> To: Wang, Zhihong ; dev@dpdk.org >> Cc: yuanhan.liu@linux.intel.com; thomas.monjalon@6wind.com >> Subject: Re: [PATCH v5 5/6] vhost: batch update used ring >> >> >> >> On 09/09/2016 05:39 AM, Zhihong Wang wrote: >>> This patch enables batch update of the used ring for better efficiency. >>> >>> Signed-off-by: Zhihong Wang >>> --- >>> Changes in v4: >>> >>> 1. Free shadow used ring in the right place. >>> >>> 2. Add failure check for shadow used ring malloc. >>> >>> lib/librte_vhost/vhost.c | 20 ++++++++++++-- >>> lib/librte_vhost/vhost.h | 4 +++ >>> lib/librte_vhost/vhost_user.c | 31 +++++++++++++++++---- >>> lib/librte_vhost/virtio_net.c | 64 >> +++++++++++++++++++++++++++++++++++-------- >>> 4 files changed, 101 insertions(+), 18 deletions(-) >>> >>> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c >>> index 46095c3..cb31cdd 100644 >>> --- a/lib/librte_vhost/vhost.c >>> +++ b/lib/librte_vhost/vhost.c >>> @@ -119,10 +119,26 @@ cleanup_device(struct virtio_net *dev, int >> destroy) >>> static void >>> free_device(struct virtio_net *dev) >>> { >>> + struct vhost_virtqueue *vq_0; >>> + struct vhost_virtqueue *vq_1; >>> uint32_t i; >>> >>> - for (i = 0; i < dev->virt_qp_nb; i++) >>> - rte_free(dev->virtqueue[i * VIRTIO_QNUM]); >>> + for (i = 0; i < dev->virt_qp_nb; i++) { >>> + vq_0 = dev->virtqueue[i * VIRTIO_QNUM]; >>> + if (vq_0->shadow_used_ring) { >>> + rte_free(vq_0->shadow_used_ring); >>> + vq_0->shadow_used_ring = NULL; >>> + } >>> + >>> + vq_1 = dev->virtqueue[i * VIRTIO_QNUM + 1]; >>> + if (vq_1->shadow_used_ring) { >>> + rte_free(vq_1->shadow_used_ring); >>> + vq_1->shadow_used_ring = NULL; >>> + } >>> + >>> + /* malloc together, free together */ >>> + rte_free(vq_0); >>> + } >>> >>> rte_free(dev); >>> } >>> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h >>> index 9707dfc..381dc27 100644 >>> --- a/lib/librte_vhost/vhost.h >>> +++ b/lib/librte_vhost/vhost.h >>> @@ -85,6 +85,10 @@ struct vhost_virtqueue { >>> >>> /* Physical address of used ring, for logging */ >>> uint64_t log_guest_addr; >>> + >>> + /* Shadow used ring for performance */ >>> + struct vring_used_elem *shadow_used_ring; >>> + uint32_t shadow_used_idx; >>> } __rte_cache_aligned; >>> >>> /* Old kernels have no such macro defined */ >>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c >>> index eee99e9..d7cf1ed 100644 >>> --- a/lib/librte_vhost/vhost_user.c >>> +++ b/lib/librte_vhost/vhost_user.c >>> @@ -193,7 +193,21 @@ static int >>> vhost_user_set_vring_num(struct virtio_net *dev, >>> struct vhost_vring_state *state) >>> { >>> - dev->virtqueue[state->index]->size = state->num; >>> + struct vhost_virtqueue *vq; >>> + >>> + vq = dev->virtqueue[state->index]; >>> + vq->size = state->num; >>> + if (!vq->shadow_used_ring) { >>> + vq->shadow_used_ring = rte_malloc(NULL, >>> + vq->size * sizeof(struct vring_used_elem), >>> + RTE_CACHE_LINE_SIZE); >>> + if (!vq->shadow_used_ring) { >>> + RTE_LOG(ERR, VHOST_CONFIG, >>> + "Failed to allocate memory" >>> + " for shadow used ring.\n"); >>> + return -1; >>> + } >>> + } >>> >>> return 0; >>> } >>> @@ -611,14 +625,21 @@ static int >>> vhost_user_get_vring_base(struct virtio_net *dev, >>> struct vhost_vring_state *state) >>> { >>> + struct vhost_virtqueue *vq; >>> + >>> /* We have to stop the queue (virtio) if it is running. */ >>> if (dev->flags & VIRTIO_DEV_RUNNING) { >>> dev->flags &= ~VIRTIO_DEV_RUNNING; >>> notify_ops->destroy_device(dev->vid); >>> } >>> >>> + vq = dev->virtqueue[state->index]; >>> /* Here we are safe to get the last used index */ >>> - state->num = dev->virtqueue[state->index]->last_used_idx; >>> + state->num = vq->last_used_idx; >>> + if (vq->shadow_used_ring) { >>> + rte_free(vq->shadow_used_ring); >>> + vq->shadow_used_ring = NULL; >>> + } >>> >>> RTE_LOG(INFO, VHOST_CONFIG, >>> "vring base idx:%d file:%d\n", state->index, state->num); >>> @@ -627,10 +648,10 @@ vhost_user_get_vring_base(struct virtio_net >> *dev, >>> * sent and only sent in vhost_vring_stop. >>> * TODO: cleanup the vring, it isn't usable since here. >>> */ >>> - if (dev->virtqueue[state->index]->kickfd >= 0) >>> - close(dev->virtqueue[state->index]->kickfd); >>> + if (vq->kickfd >= 0) >>> + close(vq->kickfd); >>> >>> - dev->virtqueue[state->index]->kickfd = >> VIRTIO_UNINITIALIZED_EVENTFD; >>> + vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD; >>> >>> return 0; >>> } >>> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c >>> index b38f18f..e9f6353 100644 >>> --- a/lib/librte_vhost/virtio_net.c >>> +++ b/lib/librte_vhost/virtio_net.c >>> @@ -134,17 +134,52 @@ virtio_enqueue_offload(struct rte_mbuf >> *m_buf, struct virtio_net_hdr *net_hdr) >>> } >>> >>> static inline void __attribute__((always_inline)) >>> -update_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq, >>> - uint32_t desc_chain_head, uint32_t desc_chain_len) >>> +update_used_ring(struct vhost_virtqueue *vq, uint32_t >> desc_chain_head, >>> + uint32_t desc_chain_len) >>> { >>> - uint32_t used_idx = vq->last_used_idx & (vq->size - 1); >>> - >>> - vq->used->ring[used_idx].id = desc_chain_head; >>> - vq->used->ring[used_idx].len = desc_chain_len; >>> + vq->shadow_used_ring[vq->shadow_used_idx].id = >> desc_chain_head; >>> + vq->shadow_used_ring[vq->shadow_used_idx].len = >> desc_chain_len; >>> + vq->shadow_used_idx++; >>> vq->last_used_idx++; >>> - vhost_log_used_vring(dev, vq, offsetof(struct vring_used, >>> - ring[used_idx]), >>> - sizeof(vq->used->ring[used_idx])); >>> +} >>> + >>> +static inline void __attribute__((always_inline)) >>> +flush_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq, >>> + uint32_t used_idx_start) >>> +{ >>> + if (used_idx_start + vq->shadow_used_idx < vq->size) { >>> + rte_memcpy(&vq->used->ring[used_idx_start], >>> + &vq->shadow_used_ring[0], >>> + vq->shadow_used_idx * >>> + sizeof(struct vring_used_elem)); >>> + vhost_log_used_vring(dev, vq, >>> + offsetof(struct vring_used, >>> + ring[used_idx_start]), >>> + vq->shadow_used_idx * >>> + sizeof(struct vring_used_elem)); >>> + } else { >>> + uint32_t part_1 = vq->size - used_idx_start; >>> + uint32_t part_2 = vq->shadow_used_idx - part_1; >>> + >>> + rte_memcpy(&vq->used->ring[used_idx_start], >>> + &vq->shadow_used_ring[0], >>> + part_1 * >>> + sizeof(struct vring_used_elem)); >>> + vhost_log_used_vring(dev, vq, >>> + offsetof(struct vring_used, >>> + ring[used_idx_start]), >>> + part_1 * >>> + sizeof(struct vring_used_elem)); >>> + rte_memcpy(&vq->used->ring[0], >>> + &vq->shadow_used_ring[part_1], >>> + part_2 * >>> + sizeof(struct vring_used_elem)); >>> + vhost_log_used_vring(dev, vq, >>> + offsetof(struct vring_used, >>> + ring[0]), >>> + part_2 * >>> + sizeof(struct vring_used_elem)); >>> + } >>> } >> Is expanding the code done for performance purpose? > > Hi Maxime, > > Yes theoretically this has the least branch number. > And I think the logic is simpler this way. Ok, in that case, maybe you could create a function to do the rte_memcpy and the vhost_log_used on a given range. I don't have a strong opinion on this, if Yuanhan is fine with current code, that's ok for me. Thanks, Maxime > > Thanks > Zhihong > >> Or maybe we could have a loop to do that? >> Something like this (not compiled, not tested): >> >> static inline void __attribute__((always_inline)) >> flush_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq, >> { >> uint32_t to = used_idx_start; >> uint32_t from = 0; >> uint32_t count; >> >> if (used_idx_start + vq->shadow_used_idx < vq->size) >> count = vq->shadow_used_idx; >> else >> count = vq->size - used_idx_start; >> >> do { >> rte_memcpy(&vq->used->ring[to], >> &vq->shadow_used_ring[from], >> count * sizeof(struct vring_used_elem)); >> vhost_log_used_vring(dev, vq, >> offsetof(struct vring_used, ring[to]), >> count * sizeof(struct vring_used_elem)); >> >> to = (to + count) & (vq->size - 1); >> from += count; >> count = vq->shadow_used_idx - count; >> } while (count); >> } >> >> Regards, >> Maxime