From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tiwei Bie Subject: [PATCH net-next v3 06/13] virtio_ring: introduce helper for indirect feature Date: Wed, 21 Nov 2018 18:03:23 +0800 Message-ID: <20181121100330.24846-7-tiwei.bie@intel.com> References: <20181121100330.24846-1-tiwei.bie@intel.com> Cc: wexu@redhat.com, jfreimann@redhat.com, maxime.coquelin@redhat.com, tiwei.bie@intel.com To: mst@redhat.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, virtio-dev@lists.oasis-open.org Return-path: Received: from mga18.intel.com ([134.134.136.126]:14789 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729575AbeKUUj0 (ORCPT ); Wed, 21 Nov 2018 15:39:26 -0500 In-Reply-To: <20181121100330.24846-1-tiwei.bie@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: Introduce a helper to check whether we will use indirect feature. It will be used by packed ring too. Signed-off-by: Tiwei Bie --- drivers/virtio/virtio_ring.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 10d407910aa2..d1076f28c7e9 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -145,6 +145,18 @@ struct vring_virtqueue { #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) +static inline bool virtqueue_use_indirect(struct virtqueue *_vq, + unsigned int total_sg) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + + /* + * If the host supports indirect descriptor tables, and we have multiple + * buffers, then go indirect. FIXME: tune this threshold + */ + return (vq->indirect && total_sg > 1 && vq->vq.num_free); +} + /* * Modern virtio devices have feature bits to specify whether they need a * quirk and bypass the IOMMU. If not there, just use the DMA API. @@ -324,9 +336,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, head = vq->free_head; - /* If the host supports indirect descriptor tables, and we have multiple - * buffers, then go indirect. FIXME: tune this threshold */ - if (vq->indirect && total_sg > 1 && vq->vq.num_free) + if (virtqueue_use_indirect(_vq, total_sg)) desc = alloc_indirect_split(_vq, total_sg, gfp); else { desc = NULL; -- 2.14.5