From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 1429568D1 for ; Sun, 9 Oct 2016 09:27:10 +0200 (CEST) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP; 09 Oct 2016 00:27:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,465,1473145200"; d="scan'208";a="1042270018" Received: from yliu-dev.sh.intel.com ([10.239.67.162]) by orsmga001.jf.intel.com with ESMTP; 09 Oct 2016 00:27:09 -0700 From: Yuanhan Liu To: dev@dpdk.org Cc: Maxime Coquelin , Yuanhan Liu Date: Sun, 9 Oct 2016 15:27:56 +0800 Message-Id: <1475998080-4644-4-git-send-email-yuanhan.liu@linux.intel.com> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1475998080-4644-1-git-send-email-yuanhan.liu@linux.intel.com> References: <1474604007-5221-1-git-send-email-yuanhan.liu@linux.intel.com> <1475998080-4644-1-git-send-email-yuanhan.liu@linux.intel.com> Subject: [dpdk-dev] [PATCH v3 3/7] vhost: introduce last avail idx for dequeue X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Oct 2016 07:27:12 -0000 So far, we retrieve both the used ring and avail ring idx by the var last_used_idx; it won't be a problem because the used ring is updated immediately after those avail entries are consumed. But that's not true when dequeue zero copy is enabled, that used ring is updated only when the mbuf is consumed. Thus, we need use another var to note the last avail ring idx we have consumed. Therefore, last_avail_idx is introduced. Signed-off-by: Yuanhan Liu Reviewed-by: Maxime Coquelin --- lib/librte_vhost/vhost.h | 2 +- lib/librte_vhost/vhost_user.c | 6 ++++-- lib/librte_vhost/virtio_net.c | 19 +++++++++++-------- 3 files changed, 16 insertions(+), 11 deletions(-) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index 2d52987..8565fa1 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -70,7 +70,7 @@ struct vhost_virtqueue { struct vring_used *used; uint32_t size; - /* Last index used on the available ring */ + uint16_t last_avail_idx; volatile uint16_t last_used_idx; #define VIRTIO_INVALID_EVENTFD (-1) #define VIRTIO_UNINITIALIZED_EVENTFD (-2) diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c index e651912..a92377a 100644 --- a/lib/librte_vhost/vhost_user.c +++ b/lib/librte_vhost/vhost_user.c @@ -343,7 +343,8 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr) "last_used_idx (%u) and vq->used->idx (%u) mismatches; " "some packets maybe resent for Tx and dropped for Rx\n", vq->last_used_idx, vq->used->idx); - vq->last_used_idx = vq->used->idx; + vq->last_used_idx = vq->used->idx; + vq->last_avail_idx = vq->used->idx; } vq->log_guest_addr = addr->log_guest_addr; @@ -367,7 +368,8 @@ static int vhost_user_set_vring_base(struct virtio_net *dev, struct vhost_vring_state *state) { - dev->virtqueue[state->index]->last_used_idx = state->num; + dev->virtqueue[state->index]->last_used_idx = state->num; + dev->virtqueue[state->index]->last_avail_idx = state->num; return 0; } diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index a59c39b..70301a5 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -851,16 +851,17 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id, } } - avail_idx = *((volatile uint16_t *)&vq->avail->idx); - free_entries = avail_idx - vq->last_used_idx; + free_entries = *((volatile uint16_t *)&vq->avail->idx) - + vq->last_avail_idx; if (free_entries == 0) goto out; LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__); - /* Prefetch available ring to retrieve head indexes. */ - used_idx = vq->last_used_idx & (vq->size - 1); - rte_prefetch0(&vq->avail->ring[used_idx]); + /* Prefetch available and used ring */ + avail_idx = vq->last_avail_idx & (vq->size - 1); + used_idx = vq->last_used_idx & (vq->size - 1); + rte_prefetch0(&vq->avail->ring[avail_idx]); rte_prefetch0(&vq->used->ring[used_idx]); count = RTE_MIN(count, MAX_PKT_BURST); @@ -870,8 +871,9 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id, /* Retrieve all of the head indexes first to avoid caching issues. */ for (i = 0; i < count; i++) { - used_idx = (vq->last_used_idx + i) & (vq->size - 1); - desc_indexes[i] = vq->avail->ring[used_idx]; + avail_idx = (vq->last_avail_idx + i) & (vq->size - 1); + used_idx = (vq->last_used_idx + i) & (vq->size - 1); + desc_indexes[i] = vq->avail->ring[avail_idx]; vq->used->ring[used_idx].id = desc_indexes[i]; vq->used->ring[used_idx].len = 0; @@ -921,7 +923,8 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id, rte_smp_wmb(); rte_smp_rmb(); vq->used->idx += i; - vq->last_used_idx += i; + vq->last_avail_idx += i; + vq->last_used_idx += i; vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx), sizeof(vq->used->idx)); -- 1.9.0