On Thu, 25 Jan 2024 11:39:20 +0800, Jason Wang <jasow...@redhat.com> wrote: > On Tue, Jan 16, 2024 at 3:59 PM Xuan Zhuo <xuanz...@linux.alibaba.com> wrote: > > > > If the xsk is enabling, the xsk tx will share the send queue. > > Any reason for this? Technically, virtio-net can work as other NIC > like 256 queues. There could be some work like optimizing the > interrupt allocations etc.
Just like the logic of XDP_TX. Now the virtio spec does not allow to add new dynamic queues. As I know, most hypervisors just support few queues. The num of queues is not bigger than the cpu num. So the best way is to share the send queues. Parav and I tried to introduce dynamic queues. But that is dropped. Before that I think we can share the send queues. > > > But the xsk requires that the send queue use the premapped mode. > > So the send queue must support premapped mode. > > > > command: pktgen_sample01_simple.sh -i eth0 -s 16/1400 -d 10.0.0.123 -m > > 00:16:3e:12:e1:3e -n 0 -p 100 > > machine: ecs.ebmg6e.26xlarge of Aliyun > > cpu: Intel(R) Xeon(R) Platinum 8269CY CPU @ 2.50GHz > > iommu mode: intel_iommu=on iommu.strict=1 iommu=nopt > > > > | iommu off | iommu on > > ----------------------|----------------------------------------------------- > > | 16 | 1400 | 16 | 1400 > > ----------------------|----------------------------------------------------- > > Before: |1716796.00 | 1581829.00 | 390756.00 | 374493.00 > > After(premapped off): |1733794.00 | 1576259.00 | 390189.00 | 378128.00 > > After(premapped on): |1707107.00 | 1562917.00 | 385667.00 | 373584.00 > > > > Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com> > > --- > > drivers/net/virtio/main.c | 119 ++++++++++++++++++++++++++++---- > > drivers/net/virtio/virtio_net.h | 10 ++- > > 2 files changed, 116 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c > > index 4fbf612da235..53143f95a3a0 100644 > > --- a/drivers/net/virtio/main.c > > +++ b/drivers/net/virtio/main.c > > @@ -168,13 +168,39 @@ static struct xdp_frame *ptr_to_xdp(void *ptr) > > return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG); > > } > > > > +static void virtnet_sq_unmap_buf(struct virtnet_sq *sq, struct > > virtio_dma_head *dma) > > +{ > > + int i; > > + > > + if (!dma) > > + return; > > + > > + for (i = 0; i < dma->next; ++i) > > + virtqueue_dma_unmap_single_attrs(sq->vq, > > + dma->items[i].addr, > > + dma->items[i].length, > > + DMA_TO_DEVICE, 0); > > + dma->next = 0; > > +} > > + > > static void __free_old_xmit(struct virtnet_sq *sq, bool in_napi, > > u64 *bytes, u64 *packets) > > { > > + struct virtio_dma_head *dma; > > unsigned int len; > > void *ptr; > > > > - while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) { > > + if (virtqueue_get_dma_premapped(sq->vq)) { > > Any chance this.can be false? __free_old_xmit is the common path. The virtqueue_get_dma_premapped() is used to check whether the sq is premapped mode. > > > + dma = &sq->dma.head; > > + dma->num = ARRAY_SIZE(sq->dma.items); > > + dma->next = 0; > > Btw, I found in the case of RX we have: > > virtnet_rq_alloc(): > > alloc_frag->offset = sizeof(*dma); > > This seems to defeat frag coalescing when the memory is highly > fragmented or high order allocation is disallowed. > > Any idea to solve this? On the rq premapped pathset, I answered this. http://lore.kernel.org/all/1692156147.7470396-3-xuanz...@linux.alibaba.com > > > + } else { > > + dma = NULL; > > + } > > + > > + while ((ptr = virtqueue_get_buf_ctx_dma(sq->vq, &len, dma, NULL)) > > != NULL) { > > + virtnet_sq_unmap_buf(sq, dma); > > + > > if (!is_xdp_frame(ptr)) { > > struct sk_buff *skb = ptr; > > > > @@ -572,16 +598,70 @@ static void *virtnet_rq_alloc(struct virtnet_rq *rq, > > u32 size, gfp_t gfp) > > return buf; > > } > > > > -static void virtnet_rq_set_premapped(struct virtnet_info *vi) > > +static void virtnet_set_premapped(struct virtnet_info *vi) > > { > > int i; > > > > - /* disable for big mode */ > > - if (!vi->mergeable_rx_bufs && vi->big_packets) > > - return; > > + for (i = 0; i < vi->max_queue_pairs; i++) { > > + virtqueue_set_dma_premapped(vi->sq[i].vq); > > > > - for (i = 0; i < vi->max_queue_pairs; i++) > > - virtqueue_set_dma_premapped(vi->rq[i].vq); > > + /* TODO for big mode */ > > Btw, how hard to support big mode? If we can do premapping for that > code could be simplified. > > (There are vendors that doesn't support mergeable rx buffers). I will do that after these patch-sets > > > + if (vi->mergeable_rx_bufs || !vi->big_packets) > > + virtqueue_set_dma_premapped(vi->rq[i].vq); > > + } > > +} > > + > > +static void virtnet_sq_unmap_sg(struct virtnet_sq *sq, u32 num) > > +{ > > + struct scatterlist *sg; > > + u32 i; > > + > > + for (i = 0; i < num; ++i) { > > + sg = &sq->sg[i]; > > + > > + virtqueue_dma_unmap_single_attrs(sq->vq, > > + sg->dma_address, > > + sg->length, > > + DMA_TO_DEVICE, 0); > > + } > > +} > > + > > +static int virtnet_sq_map_sg(struct virtnet_sq *sq, u32 num) > > +{ > > + struct scatterlist *sg; > > + u32 i; > > + > > + for (i = 0; i < num; ++i) { > > + sg = &sq->sg[i]; > > + sg->dma_address = virtqueue_dma_map_single_attrs(sq->vq, > > sg_virt(sg), > > + sg->length, > > + > > DMA_TO_DEVICE, 0); > > + if (virtqueue_dma_mapping_error(sq->vq, sg->dma_address)) > > + goto err; > > + } > > + > > This seems nothing virtio-net specific, let's move it to the core? This is the dma api style. And the caller can not judge it by the return value of virtqueue_dma_map_single_attrs. Thanks > > Thanks > > > > + return 0; > > + > > +err: > > + virtnet_sq_unmap_sg(sq, i); > > + return -ENOMEM; > > +} > > + > > +static int virtnet_add_outbuf(struct virtnet_sq *sq, u32 num, void *data) > > +{ > > + int ret; > > + > > + if (virtqueue_get_dma_premapped(sq->vq)) { > > + ret = virtnet_sq_map_sg(sq, num); > > + if (ret) > > + return -ENOMEM; > > + } > > + > > + ret = virtqueue_add_outbuf(sq->vq, sq->sg, num, data, GFP_ATOMIC); > > + if (ret && virtqueue_get_dma_premapped(sq->vq)) > > + virtnet_sq_unmap_sg(sq, num); > > + > > + return ret; > > } > > > > static void free_old_xmit(struct virtnet_sq *sq, bool in_napi) > > @@ -687,8 +767,7 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info > > *vi, > > skb_frag_size(frag), skb_frag_off(frag)); > > } > > > > - err = virtqueue_add_outbuf(sq->vq, sq->sg, nr_frags + 1, > > - xdp_to_ptr(xdpf), GFP_ATOMIC); > > + err = virtnet_add_outbuf(sq, nr_frags + 1, xdp_to_ptr(xdpf)); > > if (unlikely(err)) > > return -ENOSPC; /* Caller handle free/refcnt */ > > > > @@ -2154,7 +2233,7 @@ static int xmit_skb(struct virtnet_sq *sq, struct > > sk_buff *skb) > > return num_sg; > > num_sg++; > > } > > - return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, > > GFP_ATOMIC); > > + return virtnet_add_outbuf(sq, num_sg, skb); > > } > > > > static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > > @@ -4011,9 +4090,25 @@ static void free_receive_page_frags(struct > > virtnet_info *vi) > > > > static void virtnet_sq_free_unused_bufs(struct virtqueue *vq) > > { > > + struct virtnet_info *vi = vq->vdev->priv; > > + struct virtio_dma_head *dma; > > + struct virtnet_sq *sq; > > + int i = vq2txq(vq); > > void *buf; > > > > - while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) { > > + sq = &vi->sq[i]; > > + > > + if (virtqueue_get_dma_premapped(sq->vq)) { > > + dma = &sq->dma.head; > > + dma->num = ARRAY_SIZE(sq->dma.items); > > + dma->next = 0; > > + } else { > > + dma = NULL; > > + } > > + > > + while ((buf = virtqueue_detach_unused_buf_dma(vq, dma)) != NULL) { > > + virtnet_sq_unmap_buf(sq, dma); > > + > > if (!is_xdp_frame(buf)) > > dev_kfree_skb(buf); > > else > > @@ -4228,7 +4323,7 @@ static int init_vqs(struct virtnet_info *vi) > > if (ret) > > goto err_free; > > > > - virtnet_rq_set_premapped(vi); > > + virtnet_set_premapped(vi); > > > > cpus_read_lock(); > > virtnet_set_affinity(vi); > > diff --git a/drivers/net/virtio/virtio_net.h > > b/drivers/net/virtio/virtio_net.h > > index 066a2b9d2b3c..dda144cc91c7 100644 > > --- a/drivers/net/virtio/virtio_net.h > > +++ b/drivers/net/virtio/virtio_net.h > > @@ -48,13 +48,21 @@ struct virtnet_rq_dma { > > u16 need_sync; > > }; > > > > +struct virtnet_sq_dma { > > + struct virtio_dma_head head; > > + struct virtio_dma_item items[MAX_SKB_FRAGS + 2]; > > +}; > > + > > /* Internal representation of a send virtqueue */ > > struct virtnet_sq { > > /* Virtqueue associated with this virtnet_sq */ > > struct virtqueue *vq; > > > > /* TX: fragments + linear part + virtio header */ > > - struct scatterlist sg[MAX_SKB_FRAGS + 2]; > > + union { > > + struct scatterlist sg[MAX_SKB_FRAGS + 2]; > > + struct virtnet_sq_dma dma; > > + }; > > > > /* Name of the send queue: output.$index */ > > char name[16]; > > -- > > 2.32.0.3.g01195cf9f > > >