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Message-ID: <1689736867.7075129-1-xuanzhuo@linux.alibaba.com>
Date: Wed, 19 Jul 2023 11:21:07 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>,
virtualization@...ts.linux-foundation.org,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
netdev@...r.kernel.org,
bpf@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH vhost v11 10/10] virtio_net: merge dma operation for one page
On Fri, 14 Jul 2023 06:37:10 -0400, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> On Wed, Jul 12, 2023 at 04:38:24PM +0800, Xuan Zhuo wrote:
> > On Wed, 12 Jul 2023 16:37:43 +0800, Jason Wang <jasowang@...hat.com> wrote:
> > > On Wed, Jul 12, 2023 at 4:33 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
> > > >
> > > > On Wed, 12 Jul 2023 15:54:58 +0800, Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
> > > > > On Tue, 11 Jul 2023 10:58:51 +0800, Jason Wang <jasowang@...hat.com> wrote:
> > > > > > On Tue, Jul 11, 2023 at 10:42 AM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
> > > > > > >
> > > > > > > On Tue, 11 Jul 2023 10:36:17 +0800, Jason Wang <jasowang@...hat.com> wrote:
> > > > > > > > On Mon, Jul 10, 2023 at 8:41 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
> > > > > > > > >
> > > > > > > > > On Mon, 10 Jul 2023 07:59:03 -0400, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > > > > > > > > > On Mon, Jul 10, 2023 at 06:18:30PM +0800, Xuan Zhuo wrote:
> > > > > > > > > > > On Mon, 10 Jul 2023 05:40:21 -0400, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > > > > > > > > > > > On Mon, Jul 10, 2023 at 11:42:37AM +0800, Xuan Zhuo wrote:
> > > > > > > > > > > > > Currently, the virtio core will perform a dma operation for each
> > > > > > > > > > > > > operation. Although, the same page may be operated multiple times.
> > > > > > > > > > > > >
> > > > > > > > > > > > > The driver does the dma operation and manages the dma address based the
> > > > > > > > > > > > > feature premapped of virtio core.
> > > > > > > > > > > > >
> > > > > > > > > > > > > This way, we can perform only one dma operation for the same page. In
> > > > > > > > > > > > > the case of mtu 1500, this can reduce a lot of dma operations.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Tested on Aliyun g7.4large machine, in the case of a cpu 100%, pps
> > > > > > > > > > > > > increased from 1893766 to 1901105. An increase of 0.4%.
> > > > > > > > > > > >
> > > > > > > > > > > > what kind of dma was there? an IOMMU? which vendors? in which mode
> > > > > > > > > > > > of operation?
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Do you mean this:
> > > > > > > > > > >
> > > > > > > > > > > [ 0.470816] iommu: Default domain type: Passthrough
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > With passthrough, dma API is just some indirect function calls, they do
> > > > > > > > > > not affect the performance a lot.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Yes, this benefit is worthless. I seem to have done a meaningless thing. The
> > > > > > > > > overhead of DMA I observed is indeed not too high.
> > > > > > > >
> > > > > > > > Have you measured with iommu=strict?
> > > > > > >
> > > > > > > I have not tested this way, our environment is pt, I wonder if strict is a
> > > > > > > common scenario. I can test it.
> > > > > >
> > > > > > It's not a common setup, but it's a way to stress DMA layer to see the overhead.
> > > > >
> > > > > kernel command line: intel_iommu=on iommu.strict=1 iommu.passthrough=0
> > > > >
> > > > > virtio-net without merge dma 428614.00 pps
> > > > >
> > > > > virtio-net with merge dma 742853.00 pps
> > > >
> > > >
> > > > kernel command line: intel_iommu=on iommu.strict=0 iommu.passthrough=0
> > > >
> > > > virtio-net without merge dma 775496.00 pps
> > > >
> > > > virtio-net with merge dma 1010514.00 pps
> > > >
> > > >
> > >
> > > Great, let's add those numbers to the changelog.
> >
> >
> > Yes, I will do it in next version.
> >
> >
> > Thanks.
> >
>
> You should also test without iommu but with swiotlb=force
For swiotlb, merge DMA has no benefit, because we still need to copy data from
swiotlb buffer to the origin buffer.
The benefit of the merge DMA is to reduce the operate to the iommu device.
I did some test for this. The result is same.
Thanks.
>
> But first fix the use of DMA API to actually be correct,
> otherwise you are cheating by avoiding synchronization.
>
>
>
> > >
> > > Thanks
> > >
> > > > Thanks.
> > > >
> > > > >
> > > > >
> > > > > Thanks.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >
> > > > > > Thanks
> > > > > >
> > > > > > >
> > > > > > > Thanks.
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > >
> > > > > > > > >
> > > > > > > > > Thanks.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Try e.g. bounce buffer. Which is where you will see a problem: your
> > > > > > > > > > patches won't work.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> > > > > > > > > > > >
> > > > > > > > > > > > This kind of difference is likely in the noise.
> > > > > > > > > > >
> > > > > > > > > > > It's really not high, but this is because the proportion of DMA under perf top
> > > > > > > > > > > is not high. Probably that much.
> > > > > > > > > >
> > > > > > > > > > So maybe not worth the complexity.
> > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > ---
> > > > > > > > > > > > > drivers/net/virtio_net.c | 283 ++++++++++++++++++++++++++++++++++++---
> > > > > > > > > > > > > 1 file changed, 267 insertions(+), 16 deletions(-)
> > > > > > > > > > > > >
> > > > > > > > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > > > > > > > > > > index 486b5849033d..4de845d35bed 100644
> > > > > > > > > > > > > --- a/drivers/net/virtio_net.c
> > > > > > > > > > > > > +++ b/drivers/net/virtio_net.c
> > > > > > > > > > > > > @@ -126,6 +126,27 @@ static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
> > > > > > > > > > > > > #define VIRTNET_SQ_STATS_LEN ARRAY_SIZE(virtnet_sq_stats_desc)
> > > > > > > > > > > > > #define VIRTNET_RQ_STATS_LEN ARRAY_SIZE(virtnet_rq_stats_desc)
> > > > > > > > > > > > >
> > > > > > > > > > > > > +/* The bufs on the same page may share this struct. */
> > > > > > > > > > > > > +struct virtnet_rq_dma {
> > > > > > > > > > > > > + struct virtnet_rq_dma *next;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dma_addr_t addr;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + void *buf;
> > > > > > > > > > > > > + u32 len;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + u32 ref;
> > > > > > > > > > > > > +};
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +/* Record the dma and buf. */
> > > > > > > > > > > >
> > > > > > > > > > > > I guess I see that. But why?
> > > > > > > > > > > > And these two comments are the extent of the available
> > > > > > > > > > > > documentation, that's not enough I feel.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > +struct virtnet_rq_data {
> > > > > > > > > > > > > + struct virtnet_rq_data *next;
> > > > > > > > > > > >
> > > > > > > > > > > > Is manually reimplementing a linked list the best
> > > > > > > > > > > > we can do?
> > > > > > > > > > >
> > > > > > > > > > > Yes, we can use llist.
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + void *buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + struct virtnet_rq_dma *dma;
> > > > > > > > > > > > > +};
> > > > > > > > > > > > > +
> > > > > > > > > > > > > /* Internal representation of a send virtqueue */
> > > > > > > > > > > > > struct send_queue {
> > > > > > > > > > > > > /* Virtqueue associated with this send _queue */
> > > > > > > > > > > > > @@ -175,6 +196,13 @@ struct receive_queue {
> > > > > > > > > > > > > char name[16];
> > > > > > > > > > > > >
> > > > > > > > > > > > > struct xdp_rxq_info xdp_rxq;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + struct virtnet_rq_data *data_array;
> > > > > > > > > > > > > + struct virtnet_rq_data *data_free;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + struct virtnet_rq_dma *dma_array;
> > > > > > > > > > > > > + struct virtnet_rq_dma *dma_free;
> > > > > > > > > > > > > + struct virtnet_rq_dma *last_dma;
> > > > > > > > > > > > > };
> > > > > > > > > > > > >
> > > > > > > > > > > > > /* This structure can contain rss message with maximum settings for indirection table and keysize
> > > > > > > > > > > > > @@ -549,6 +577,176 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > > > > > > > > > > > return skb;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > +static void virtnet_rq_unmap(struct receive_queue *rq, struct virtnet_rq_dma *dma)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct device *dev;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + --dma->ref;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + if (dma->ref)
> > > > > > > > > > > > > + return;
> > > > > > > > > > > > > +
> > > > > > > > > > > >
> > > > > > > > > > > > If you don't unmap there is no guarantee valid data will be
> > > > > > > > > > > > there in the buffer.
> > > > > > > > > > > >
> > > > > > > > > > > > > + dev = virtqueue_dma_dev(rq->vq);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dma_unmap_page(dev, dma->addr, dma->len, DMA_FROM_DEVICE);
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dma->next = rq->dma_free;
> > > > > > > > > > > > > + rq->dma_free = dma;
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static void *virtnet_rq_recycle_data(struct receive_queue *rq,
> > > > > > > > > > > > > + struct virtnet_rq_data *data)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + void *buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + buf = data->buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data->next = rq->data_free;
> > > > > > > > > > > > > + rq->data_free = data;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return buf;
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static struct virtnet_rq_data *virtnet_rq_get_data(struct receive_queue *rq,
> > > > > > > > > > > > > + void *buf,
> > > > > > > > > > > > > + struct virtnet_rq_dma *dma)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct virtnet_rq_data *data;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data = rq->data_free;
> > > > > > > > > > > > > + rq->data_free = data->next;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data->buf = buf;
> > > > > > > > > > > > > + data->dma = dma;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return data;
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct virtnet_rq_data *data;
> > > > > > > > > > > > > + void *buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
> > > > > > > > > > > > > + if (!buf || !rq->data_array)
> > > > > > > > > > > > > + return buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data = buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + virtnet_rq_unmap(rq, data->dma);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return virtnet_rq_recycle_data(rq, data);
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct virtnet_rq_data *data;
> > > > > > > > > > > > > + void *buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + buf = virtqueue_detach_unused_buf(rq->vq);
> > > > > > > > > > > > > + if (!buf || !rq->data_array)
> > > > > > > > > > > > > + return buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data = buf;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + virtnet_rq_unmap(rq, data->dma);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return virtnet_rq_recycle_data(rq, data);
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static int virtnet_rq_map_sg(struct receive_queue *rq, void *buf, u32 len)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct virtnet_rq_dma *dma = rq->last_dma;
> > > > > > > > > > > > > + struct device *dev;
> > > > > > > > > > > > > + u32 off, map_len;
> > > > > > > > > > > > > + dma_addr_t addr;
> > > > > > > > > > > > > + void *end;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + if (likely(dma) && buf >= dma->buf && (buf + len <= dma->buf + dma->len)) {
> > > > > > > > > > > > > + ++dma->ref;
> > > > > > > > > > > > > + addr = dma->addr + (buf - dma->buf);
> > > > > > > > > > > > > + goto ok;
> > > > > > > > > > > > > + }
> > > > > > > > > > > >
> > > > > > > > > > > > So this is the meat of the proposed optimization. I guess that
> > > > > > > > > > > > if the last buffer we allocated happens to be in the same page
> > > > > > > > > > > > as this one then they can both be mapped for DMA together.
> > > > > > > > > > >
> > > > > > > > > > > Since we use page_frag, the buffers we allocated are all continuous.
> > > > > > > > > > >
> > > > > > > > > > > > Why last one specifically? Whether next one happens to
> > > > > > > > > > > > be close depends on luck. If you want to try optimizing this
> > > > > > > > > > > > the right thing to do is likely by using a page pool.
> > > > > > > > > > > > There's actually work upstream on page pool, look it up.
> > > > > > > > > > >
> > > > > > > > > > > As we discussed in another thread, the page pool is first used for xdp. Let's
> > > > > > > > > > > transform it step by step.
> > > > > > > > > > >
> > > > > > > > > > > Thanks.
> > > > > > > > > >
> > > > > > > > > > ok so this should wait then?
> > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + end = buf + len - 1;
> > > > > > > > > > > > > + off = offset_in_page(end);
> > > > > > > > > > > > > + map_len = len + PAGE_SIZE - off;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dev = virtqueue_dma_dev(rq->vq);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + addr = dma_map_page_attrs(dev, virt_to_page(buf), offset_in_page(buf),
> > > > > > > > > > > > > + map_len, DMA_FROM_DEVICE, 0);
> > > > > > > > > > > > > + if (addr == DMA_MAPPING_ERROR)
> > > > > > > > > > > > > + return -ENOMEM;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dma = rq->dma_free;
> > > > > > > > > > > > > + rq->dma_free = dma->next;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + dma->ref = 1;
> > > > > > > > > > > > > + dma->buf = buf;
> > > > > > > > > > > > > + dma->addr = addr;
> > > > > > > > > > > > > + dma->len = map_len;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq->last_dma = dma;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +ok:
> > > > > > > > > > > > > + sg_init_table(rq->sg, 1);
> > > > > > > > > > > > > + rq->sg[0].dma_address = addr;
> > > > > > > > > > > > > + rq->sg[0].length = len;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return 0;
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +static int virtnet_rq_merge_map_init(struct virtnet_info *vi)
> > > > > > > > > > > > > +{
> > > > > > > > > > > > > + struct receive_queue *rq;
> > > > > > > > > > > > > + int i, err, j, num;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + /* disable for big mode */
> > > > > > > > > > > > > + if (!vi->mergeable_rx_bufs && vi->big_packets)
> > > > > > > > > > > > > + return 0;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > > > > > > > > > > + err = virtqueue_set_premapped(vi->rq[i].vq);
> > > > > > > > > > > > > + if (err)
> > > > > > > > > > > > > + continue;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq = &vi->rq[i];
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + num = virtqueue_get_vring_size(rq->vq);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq->data_array = kmalloc_array(num, sizeof(*rq->data_array), GFP_KERNEL);
> > > > > > > > > > > > > + if (!rq->data_array)
> > > > > > > > > > > > > + goto err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq->dma_array = kmalloc_array(num, sizeof(*rq->dma_array), GFP_KERNEL);
> > > > > > > > > > > > > + if (!rq->dma_array)
> > > > > > > > > > > > > + goto err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + for (j = 0; j < num; ++j) {
> > > > > > > > > > > > > + rq->data_array[j].next = rq->data_free;
> > > > > > > > > > > > > + rq->data_free = &rq->data_array[j];
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq->dma_array[j].next = rq->dma_free;
> > > > > > > > > > > > > + rq->dma_free = &rq->dma_array[j];
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return 0;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +err:
> > > > > > > > > > > > > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > > > > > > > > > > + struct receive_queue *rq;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + rq = &vi->rq[i];
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + kfree(rq->dma_array);
> > > > > > > > > > > > > + kfree(rq->data_array);
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return -ENOMEM;
> > > > > > > > > > > > > +}
> > > > > > > > > > > > > +
> > > > > > > > > > > > > static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
> > > > > > > > > > > > > {
> > > > > > > > > > > > > unsigned int len;
> > > > > > > > > > > > > @@ -835,7 +1033,7 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
> > > > > > > > > > > > > void *buf;
> > > > > > > > > > > > > int off;
> > > > > > > > > > > > >
> > > > > > > > > > > > > - buf = virtqueue_get_buf(rq->vq, &buflen);
> > > > > > > > > > > > > + buf = virtnet_rq_get_buf(rq, &buflen, NULL);
> > > > > > > > > > > > > if (unlikely(!buf))
> > > > > > > > > > > > > goto err_buf;
> > > > > > > > > > > > >
> > > > > > > > > > > > > @@ -1126,7 +1324,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
> > > > > > > > > > > > > return -EINVAL;
> > > > > > > > > > > > >
> > > > > > > > > > > > > while (--*num_buf > 0) {
> > > > > > > > > > > > > - buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
> > > > > > > > > > > > > + buf = virtnet_rq_get_buf(rq, &len, &ctx);
> > > > > > > > > > > > > if (unlikely(!buf)) {
> > > > > > > > > > > > > pr_debug("%s: rx error: %d buffers out of %d missing\n",
> > > > > > > > > > > > > dev->name, *num_buf,
> > > > > > > > > > > > > @@ -1351,7 +1549,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > > > while (--num_buf) {
> > > > > > > > > > > > > int num_skb_frags;
> > > > > > > > > > > > >
> > > > > > > > > > > > > - buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
> > > > > > > > > > > > > + buf = virtnet_rq_get_buf(rq, &len, &ctx);
> > > > > > > > > > > > > if (unlikely(!buf)) {
> > > > > > > > > > > > > pr_debug("%s: rx error: %d buffers out of %d missing\n",
> > > > > > > > > > > > > dev->name, num_buf,
> > > > > > > > > > > > > @@ -1414,7 +1612,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > > > err_skb:
> > > > > > > > > > > > > put_page(page);
> > > > > > > > > > > > > while (num_buf-- > 1) {
> > > > > > > > > > > > > - buf = virtqueue_get_buf(rq->vq, &len);
> > > > > > > > > > > > > + buf = virtnet_rq_get_buf(rq, &len, NULL);
> > > > > > > > > > > > > if (unlikely(!buf)) {
> > > > > > > > > > > > > pr_debug("%s: rx error: %d buffers missing\n",
> > > > > > > > > > > > > dev->name, num_buf);
> > > > > > > > > > > > > @@ -1529,6 +1727,7 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
> > > > > > > > > > > > > unsigned int xdp_headroom = virtnet_get_headroom(vi);
> > > > > > > > > > > > > void *ctx = (void *)(unsigned long)xdp_headroom;
> > > > > > > > > > > > > int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
> > > > > > > > > > > > > + struct virtnet_rq_data *data;
> > > > > > > > > > > > > int err;
> > > > > > > > > > > > >
> > > > > > > > > > > > > len = SKB_DATA_ALIGN(len) +
> > > > > > > > > > > > > @@ -1539,11 +1738,34 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
> > > > > > > > > > > > > buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
> > > > > > > > > > > > > get_page(alloc_frag->page);
> > > > > > > > > > > > > alloc_frag->offset += len;
> > > > > > > > > > > > > - sg_init_one(rq->sg, buf + VIRTNET_RX_PAD + xdp_headroom,
> > > > > > > > > > > > > - vi->hdr_len + GOOD_PACKET_LEN);
> > > > > > > > > > > > > - err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + if (rq->data_array) {
> > > > > > > > > > > > > + err = virtnet_rq_map_sg(rq, buf + VIRTNET_RX_PAD + xdp_headroom,
> > > > > > > > > > > > > + vi->hdr_len + GOOD_PACKET_LEN);
> > > > > > > > > > > > > + if (err)
> > > > > > > > > > > > > + goto map_err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data = virtnet_rq_get_data(rq, buf, rq->last_dma);
> > > > > > > > > > > > > + } else {
> > > > > > > > > > > > > + sg_init_one(rq->sg, buf + VIRTNET_RX_PAD + xdp_headroom,
> > > > > > > > > > > > > + vi->hdr_len + GOOD_PACKET_LEN);
> > > > > > > > > > > > > + data = (void *)buf;
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, data, ctx, gfp);
> > > > > > > > > > > > > if (err < 0)
> > > > > > > > > > > > > - put_page(virt_to_head_page(buf));
> > > > > > > > > > > > > + goto add_err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +add_err:
> > > > > > > > > > > > > + if (rq->data_array) {
> > > > > > > > > > > > > + virtnet_rq_unmap(rq, data->dma);
> > > > > > > > > > > > > + virtnet_rq_recycle_data(rq, data);
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +map_err:
> > > > > > > > > > > > > + put_page(virt_to_head_page(buf));
> > > > > > > > > > > > > return err;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > @@ -1620,6 +1842,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
> > > > > > > > > > > > > unsigned int headroom = virtnet_get_headroom(vi);
> > > > > > > > > > > > > unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
> > > > > > > > > > > > > unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
> > > > > > > > > > > > > + struct virtnet_rq_data *data;
> > > > > > > > > > > > > char *buf;
> > > > > > > > > > > > > void *ctx;
> > > > > > > > > > > > > int err;
> > > > > > > > > > > > > @@ -1650,12 +1873,32 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
> > > > > > > > > > > > > alloc_frag->offset += hole;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > - sg_init_one(rq->sg, buf, len);
> > > > > > > > > > > > > + if (rq->data_array) {
> > > > > > > > > > > > > + err = virtnet_rq_map_sg(rq, buf, len);
> > > > > > > > > > > > > + if (err)
> > > > > > > > > > > > > + goto map_err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + data = virtnet_rq_get_data(rq, buf, rq->last_dma);
> > > > > > > > > > > > > + } else {
> > > > > > > > > > > > > + sg_init_one(rq->sg, buf, len);
> > > > > > > > > > > > > + data = (void *)buf;
> > > > > > > > > > > > > + }
> > > > > > > > > > > > > +
> > > > > > > > > > > > > ctx = mergeable_len_to_ctx(len + room, headroom);
> > > > > > > > > > > > > - err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
> > > > > > > > > > > > > + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, data, ctx, gfp);
> > > > > > > > > > > > > if (err < 0)
> > > > > > > > > > > > > - put_page(virt_to_head_page(buf));
> > > > > > > > > > > > > + goto add_err;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + return 0;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > +add_err:
> > > > > > > > > > > > > + if (rq->data_array) {
> > > > > > > > > > > > > + virtnet_rq_unmap(rq, data->dma);
> > > > > > > > > > > > > + virtnet_rq_recycle_data(rq, data);
> > > > > > > > > > > > > + }
> > > > > > > > > > > > >
> > > > > > > > > > > > > +map_err:
> > > > > > > > > > > > > + put_page(virt_to_head_page(buf));
> > > > > > > > > > > > > return err;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > @@ -1775,13 +2018,13 @@ static int virtnet_receive(struct receive_queue *rq, int budget,
> > > > > > > > > > > > > void *ctx;
> > > > > > > > > > > > >
> > > > > > > > > > > > > while (stats.packets < budget &&
> > > > > > > > > > > > > - (buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx))) {
> > > > > > > > > > > > > + (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
> > > > > > > > > > > > > receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
> > > > > > > > > > > > > stats.packets++;
> > > > > > > > > > > > > }
> > > > > > > > > > > > > } else {
> > > > > > > > > > > > > while (stats.packets < budget &&
> > > > > > > > > > > > > - (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
> > > > > > > > > > > > > + (buf = virtnet_rq_get_buf(rq, &len, NULL)) != NULL) {
> > > > > > > > > > > > > receive_buf(vi, rq, buf, len, NULL, xdp_xmit, &stats);
> > > > > > > > > > > > > stats.packets++;
> > > > > > > > > > > > > }
> > > > > > > > > > > > > @@ -3514,6 +3757,9 @@ static void virtnet_free_queues(struct virtnet_info *vi)
> > > > > > > > > > > > > for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > > > > > > > > > > __netif_napi_del(&vi->rq[i].napi);
> > > > > > > > > > > > > __netif_napi_del(&vi->sq[i].napi);
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + kfree(vi->rq[i].data_array);
> > > > > > > > > > > > > + kfree(vi->rq[i].dma_array);
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > /* We called __netif_napi_del(),
> > > > > > > > > > > > > @@ -3591,9 +3837,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > > > > > > > > > > - struct virtqueue *vq = vi->rq[i].vq;
> > > > > > > > > > > > > - while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > > > > > > > > > > > > - virtnet_rq_free_unused_buf(vq, buf);
> > > > > > > > > > > > > + struct receive_queue *rq = &vi->rq[i];
> > > > > > > > > > > > > +
> > > > > > > > > > > > > + while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
> > > > > > > > > > > > > + virtnet_rq_free_unused_buf(rq->vq, buf);
> > > > > > > > > > > > > cond_resched();
> > > > > > > > > > > > > }
> > > > > > > > > > > > > }
> > > > > > > > > > > > > @@ -3767,6 +4014,10 @@ static int init_vqs(struct virtnet_info *vi)
> > > > > > > > > > > > > if (ret)
> > > > > > > > > > > > > goto err_free;
> > > > > > > > > > > > >
> > > > > > > > > > > > > + ret = virtnet_rq_merge_map_init(vi);
> > > > > > > > > > > > > + if (ret)
> > > > > > > > > > > > > + goto err_free;
> > > > > > > > > > > > > +
> > > > > > > > > > > > > cpus_read_lock();
> > > > > > > > > > > > > virtnet_set_affinity(vi);
> > > > > > > > > > > > > cpus_read_unlock();
> > > > > > > > > > > > > --
> > > > > > > > > > > > > 2.32.0.3.g01195cf9f
> > > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
>
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