From 5e01d2f91df62be4d6f282149bc2a8858992ceca Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 7 Apr 2010 21:01:41 -0700 Subject: [PATCH] virtio-net: move sg off stack Move sg structure off stack and into virtnet_info structure. This helps remove extra sg_init_table calls as well as reduce stack usage. Signed-off-by: Michael S. Tsirkin Tested-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/virtio_net.c | 52 +++++++++++++++++++--------------------- 1 file changed, 25 insertions(+), 27 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ecec9a8527f3..b81e452d4ba2 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -39,8 +39,7 @@ module_param(gso, bool, 0444); #define VIRTNET_SEND_COMMAND_SG_MAX 2 -struct virtnet_info -{ +struct virtnet_info { struct virtio_device *vdev; struct virtqueue *rvq, *svq, *cvq; struct net_device *dev; @@ -61,6 +60,10 @@ struct virtnet_info /* Chain pages by the private ptr. */ struct page *pages; + + /* fragments + linear part + virtio header */ + struct scatterlist rx_sg[MAX_SKB_FRAGS + 2]; + struct scatterlist tx_sg[MAX_SKB_FRAGS + 2]; }; struct skb_vnet_hdr { @@ -323,10 +326,8 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) { struct sk_buff *skb; struct skb_vnet_hdr *hdr; - struct scatterlist sg[2]; int err; - sg_init_table(sg, 2); skb = netdev_alloc_skb_ip_align(vi->dev, MAX_PACKET_LEN); if (unlikely(!skb)) return -ENOMEM; @@ -334,11 +335,11 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) skb_put(skb, MAX_PACKET_LEN); hdr = skb_vnet_hdr(skb); - sg_set_buf(sg, &hdr->hdr, sizeof hdr->hdr); + sg_set_buf(vi->rx_sg, &hdr->hdr, sizeof hdr->hdr); - skb_to_sgvec(skb, sg + 1, 0, skb->len); + skb_to_sgvec(skb, vi->rx_sg + 1, 0, skb->len); - err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, 2, skb); + err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, 2, skb); if (err < 0) dev_kfree_skb(skb); @@ -347,13 +348,11 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) { - struct scatterlist sg[MAX_SKB_FRAGS + 2]; struct page *first, *list = NULL; char *p; int i, err, offset; - sg_init_table(sg, MAX_SKB_FRAGS + 2); - /* page in sg[MAX_SKB_FRAGS + 1] is list tail */ + /* page in vi->rx_sg[MAX_SKB_FRAGS + 1] is list tail */ for (i = MAX_SKB_FRAGS + 1; i > 1; --i) { first = get_a_page(vi, gfp); if (!first) { @@ -361,7 +360,7 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) give_pages(vi, list); return -ENOMEM; } - sg_set_buf(&sg[i], page_address(first), PAGE_SIZE); + sg_set_buf(&vi->rx_sg[i], page_address(first), PAGE_SIZE); /* chain new page in list head to match sg */ first->private = (unsigned long)list; @@ -375,17 +374,17 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) } p = page_address(first); - /* sg[0], sg[1] share the same page */ - /* a separated sg[0] for virtio_net_hdr only during to QEMU bug*/ - sg_set_buf(&sg[0], p, sizeof(struct virtio_net_hdr)); + /* vi->rx_sg[0], vi->rx_sg[1] share the same page */ + /* a separated vi->rx_sg[0] for virtio_net_hdr only due to QEMU bug */ + sg_set_buf(&vi->rx_sg[0], p, sizeof(struct virtio_net_hdr)); - /* sg[1] for data packet, from offset */ + /* vi->rx_sg[1] for data packet, from offset */ offset = sizeof(struct padded_vnet_hdr); - sg_set_buf(&sg[1], p + offset, PAGE_SIZE - offset); + sg_set_buf(&vi->rx_sg[1], p + offset, PAGE_SIZE - offset); /* chain first in list head */ first->private = (unsigned long)list; - err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, MAX_SKB_FRAGS + 2, + err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, MAX_SKB_FRAGS + 2, first); if (err < 0) give_pages(vi, first); @@ -396,16 +395,15 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp) { struct page *page; - struct scatterlist sg; int err; page = get_a_page(vi, gfp); if (!page) return -ENOMEM; - sg_init_one(&sg, page_address(page), PAGE_SIZE); + sg_init_one(vi->rx_sg, page_address(page), PAGE_SIZE); - err = vi->rvq->vq_ops->add_buf(vi->rvq, &sg, 0, 1, page); + err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, 1, page); if (err < 0) give_pages(vi, page); @@ -514,12 +512,9 @@ static unsigned int free_old_xmit_skbs(struct virtnet_info *vi) static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) { - struct scatterlist sg[2+MAX_SKB_FRAGS]; struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb); const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest; - sg_init_table(sg, 2+MAX_SKB_FRAGS); - pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest); if (skb->ip_summed == CHECKSUM_PARTIAL) { @@ -553,12 +548,13 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) /* Encode metadata header at front. */ if (vi->mergeable_rx_bufs) - sg_set_buf(sg, &hdr->mhdr, sizeof hdr->mhdr); + sg_set_buf(vi->tx_sg, &hdr->mhdr, sizeof hdr->mhdr); else - sg_set_buf(sg, &hdr->hdr, sizeof hdr->hdr); + sg_set_buf(vi->tx_sg, &hdr->hdr, sizeof hdr->hdr); - hdr->num_sg = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1; - return vi->svq->vq_ops->add_buf(vi->svq, sg, hdr->num_sg, 0, skb); + hdr->num_sg = skb_to_sgvec(skb, vi->tx_sg + 1, 0, skb->len) + 1; + return vi->svq->vq_ops->add_buf(vi->svq, vi->tx_sg, hdr->num_sg, + 0, skb); } static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) @@ -940,6 +936,8 @@ static int virtnet_probe(struct virtio_device *vdev) vdev->priv = vi; vi->pages = NULL; INIT_DELAYED_WORK(&vi->refill, refill_work); + sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg)); + sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg)); /* If we can receive ANY GSO packets, we must allocate large ones. */ if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) || -- 2.30.2