From patchwork Thu Apr 21 17:18:12 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huawei Xie X-Patchwork-Id: 12198 X-Patchwork-Delegate: yuanhan.liu@linux.intel.com Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [IPv6:::1]) by dpdk.org (Postfix) with ESMTP id 7542C2E83; Fri, 22 Apr 2016 11:12:39 +0200 (CEST) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id 9ACCD2C4B for ; Fri, 22 Apr 2016 11:12:37 +0200 (CEST) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP; 22 Apr 2016 02:12:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,516,1455004800"; d="scan'208";a="937881742" Received: from dpdk15.sh.intel.com ([10.239.129.25]) by orsmga001.jf.intel.com with ESMTP; 22 Apr 2016 02:12:36 -0700 From: Huawei Xie To: dev@dpdk.org Date: Fri, 22 Apr 2016 01:18:12 +0800 Message-Id: <1461259092-9309-1-git-send-email-huawei.xie@intel.com> X-Mailer: git-send-email 1.8.1.4 Subject: [dpdk-dev] [RFC PATCH] avail idx update optimizations 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" eliminate unnecessary cache to cache transfer between virtio and vhost core --- drivers/net/virtio/virtqueue.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h index 4e9239e..8c46a83 100644 --- a/drivers/net/virtio/virtqueue.h +++ b/drivers/net/virtio/virtqueue.h @@ -302,7 +302,8 @@ vq_update_avail_ring(struct virtqueue *vq, uint16_t desc_idx) * descriptor. */ avail_idx = (uint16_t)(vq->vq_avail_idx & (vq->vq_nentries - 1)); - vq->vq_ring.avail->ring[avail_idx] = desc_idx; + if (unlikely(vq->vq_ring.avail->ring[avail_idx] != desc_idx)) + vq->vq_ring.avail->ring[avail_idx] = desc_idx; vq->vq_avail_idx++; }