From patchwork Mon Dec 21 15:50:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joyce Kong X-Patchwork-Id: 85610 X-Patchwork-Delegate: maxime.coquelin@redhat.com Return-Path: X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id F1647A09EF; Mon, 21 Dec 2020 16:52:45 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 41BD7CC19; Mon, 21 Dec 2020 16:51:22 +0100 (CET) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 7F6D0CBEC for ; Mon, 21 Dec 2020 16:51:20 +0100 (CET) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A35E1042; Mon, 21 Dec 2020 07:51:20 -0800 (PST) Received: from net-arm-thunderx2-03.shanghai.arm.com (net-arm-thunderx2-03.shanghai.arm.com [10.169.208.206]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D0B003F6CF; Mon, 21 Dec 2020 07:51:17 -0800 (PST) From: Joyce Kong To: maxime.coquelin@redhat.com, chenbo.xia@intel.com, honnappa.nagarahalli@arm.com, ruifeng.wang@arm.com Cc: dev@dpdk.org, nd@arm.com Date: Mon, 21 Dec 2020 23:50:30 +0800 Message-Id: <20201221155033.6771-6-joyce.kong@arm.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201221155033.6771-1-joyce.kong@arm.com> References: <20201221155033.6771-1-joyce.kong@arm.com> MIME-Version: 1.0 Subject: [dpdk-dev] [PATCH v1 5/8] vhost: relax full barriers for desc flags 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" Relax the full read barrier to one-way barrier for desc flags in packed vring. Signed-off-by: Joyce Kong Reviewed-by: Ruifeng Wang Reviewed-by: Maxime Coquelin --- lib/librte_vhost/virtio_net.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index c912ae354..b779034dc 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -222,8 +222,9 @@ vhost_flush_dequeue_shadow_packed(struct virtio_net *dev, struct vring_used_elem_packed *used_elem = &vq->shadow_used_packed[0]; vq->desc_packed[vq->shadow_last_used_idx].id = used_elem->id; - rte_smp_wmb(); - vq->desc_packed[vq->shadow_last_used_idx].flags = used_elem->flags; + /* desc flags is the synchronization point for virtio packed vring */ + __atomic_store_n(&vq->desc_packed[vq->shadow_last_used_idx].flags, + used_elem->flags, __ATOMIC_RELEASE); vhost_log_cache_used_vring(dev, vq, vq->shadow_last_used_idx * sizeof(struct vring_packed_desc),