From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id C1BB01BCA6 for ; Thu, 20 Dec 2018 17:48:18 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E6D162DC342; Thu, 20 Dec 2018 16:48:17 +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 75C564141; Thu, 20 Dec 2018 16:47:57 +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 17:47:55 +0100 Message-Id: <20181220164755.8509-1-maxime.coquelin@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 20 Dec 2018 16:48:18 +0000 (UTC) Subject: [dpdk-dev] [PATCH v4] 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: , X-List-Received-Date: Thu, 20 Dec 2018 16:48:19 -0000 Instead of writing back descriptors chains in order, let's write the first chain flags last in order to improve batching. Also, move the write barrier in logging cache sync, so that it is done only when logging is enabled. It means there is now one more barrier for split ring when logging is enabled. With Kernel's pktgen benchmark, ~3% performance gain is measured. Signed-off-by: Maxime Coquelin --- lib/librte_vhost/vhost.h | 2 ++ lib/librte_vhost/virtio_net.c | 19 ++++++++++++++++--- 2 files changed, 18 insertions(+), 3 deletions(-) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index 3b3265c4b..7d1d8a308 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -457,6 +457,8 @@ vhost_log_cache_sync(struct virtio_net *dev, struct vhost_virtqueue *vq) !dev->log_base)) return; + rte_smp_wmb(); + log_base = (unsigned long *)(uintptr_t)dev->log_base; /* diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 8c657a101..02c1fd3a4 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 +147,13 @@ flush_shadow_used_ring_packed(struct virtio_net *dev, } } - rte_smp_wmb(); + vq->desc_packed[head_idx].flags = head_flags; + + 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); } -- 2.17.2