From patchwork Thu Dec 20 10:00:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Coquelin X-Patchwork-Id: 49164 X-Patchwork-Delegate: maxime.coquelin@redhat.com 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 724491B3B6; Thu, 20 Dec 2018 11:00:41 +0100 (CET) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id F090B1B0FF for ; Thu, 20 Dec 2018 11:00:39 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F1A8C8E5A4; Thu, 20 Dec 2018 10:00:38 +0000 (UTC) Received: from localhost.localdomain (ovpn-112-60.ams2.redhat.com [10.36.112.60]) by smtp.corp.redhat.com (Postfix) with ESMTP id B4B595EDE3; Thu, 20 Dec 2018 10:00:25 +0000 (UTC) From: Maxime Coquelin To: dev@dpdk.org, i.maximets@samsung.com, tiwei.bie@intel.com, zhihong.wang@intel.com, jfreiman@redhat.com, mst@redhat.com Cc: Maxime Coquelin Date: Thu, 20 Dec 2018 11:00:22 +0100 Message-Id: <20181220100022.3531-1-maxime.coquelin@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 20 Dec 2018 10:00:39 +0000 (UTC) Subject: [dpdk-dev] [PATCH v3] vhost: batch used descs chains write-back with packed ring 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" Instead of writing back descriptors chains in order, let's write the first chain flags last in order to improve batching. With Kernel's pktgen benchmark, ~3% performance gain is measured. Signed-off-by: Maxime Coquelin Reviewed-by: Tiwei Bie --- lib/librte_vhost/virtio_net.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 8c657a101..66ccd3c35 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -97,6 +97,8 @@ flush_shadow_used_ring_packed(struct virtio_net *dev, { int i; uint16_t used_idx = vq->last_used_idx; + uint16_t head_idx = vq->last_used_idx; + uint16_t head_flags = 0; /* Split loop in two to save memory barriers */ for (i = 0; i < vq->shadow_used_idx; i++) { @@ -126,12 +128,17 @@ flush_shadow_used_ring_packed(struct virtio_net *dev, flags &= ~VRING_DESC_F_AVAIL; } - vq->desc_packed[vq->last_used_idx].flags = flags; + if (i > 0) { + vq->desc_packed[vq->last_used_idx].flags = flags; - vhost_log_cache_used_vring(dev, vq, + vhost_log_cache_used_vring(dev, vq, vq->last_used_idx * sizeof(struct vring_packed_desc), sizeof(struct vring_packed_desc)); + } else { + head_idx = vq->last_used_idx; + head_flags = flags; + } vq->last_used_idx += vq->shadow_used_packed[i].count; if (vq->last_used_idx >= vq->size) { @@ -140,7 +147,15 @@ flush_shadow_used_ring_packed(struct virtio_net *dev, } } + vq->desc_packed[head_idx].flags = head_flags; + rte_smp_wmb(); + + vhost_log_cache_used_vring(dev, vq, + head_idx * + sizeof(struct vring_packed_desc), + sizeof(struct vring_packed_desc)); + vq->shadow_used_idx = 0; vhost_log_cache_sync(dev, vq); }