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Message-ID: <CAKhg4tLqxEiO-v-oorT0vy-X1=UbnQ0d=ZLF_HZEz8m-5+i-UA@mail.gmail.com>
Date: Thu, 6 Jul 2023 09:01:47 +0800
From: Liang Chen <liangchen.linux@...il.com>
To: Jason Wang <jasowang@...hat.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, xuanzhuo@...ux.alibaba.com,
kuba@...nel.org, edumazet@...gle.com, davem@...emloft.net,
pabeni@...hat.com, alexander.duyck@...il.com
Subject: Re: [PATCH net-next 2/5] virtio_net: Add page_pool support to improve performance
On Wed, Jul 5, 2023 at 2:05 PM Jason Wang <jasowang@...hat.com> wrote:
>
> On Wed, Jul 5, 2023 at 1:41 PM Liang Chen <liangchen.linux@...il.com> wrote:
> >
> > On Fri, Jun 9, 2023 at 10:57 AM Liang Chen <liangchen.linux@...il.com> wrote:
> > >
> > > On Thu, Jun 8, 2023 at 8:38 AM Jason Wang <jasowang@...hat.com> wrote:
> > > >
> > > > On Thu, Jun 8, 2023 at 4:17 AM Michael S. Tsirkin <mst@...hat.com> wrote:
> > > > >
> > > > > On Wed, Jun 07, 2023 at 05:08:59PM +0800, Liang Chen wrote:
> > > > > > On Tue, May 30, 2023 at 9:19 AM Liang Chen <liangchen.linux@...il.com> wrote:
> > > > > > >
> > > > > > > On Mon, May 29, 2023 at 5:55 PM Michael S. Tsirkin <mst@...hat.com> wrote:
> > > > > > > >
> > > > > > > > On Mon, May 29, 2023 at 03:27:56PM +0800, Liang Chen wrote:
> > > > > > > > > On Sun, May 28, 2023 at 2:20 PM Michael S. Tsirkin <mst@...hat.com> wrote:
> > > > > > > > > >
> > > > > > > > > > On Fri, May 26, 2023 at 01:46:18PM +0800, Liang Chen wrote:
> > > > > > > > > > > The implementation at the moment uses one page per packet in both the
> > > > > > > > > > > normal and XDP path. In addition, introducing a module parameter to enable
> > > > > > > > > > > or disable the usage of page pool (disabled by default).
> > > > > > > > > > >
> > > > > > > > > > > In single-core vm testing environments, it gives a modest performance gain
> > > > > > > > > > > in the normal path.
> > > > > > > > > > > Upstream codebase: 47.5 Gbits/sec
> > > > > > > > > > > Upstream codebase + page_pool support: 50.2 Gbits/sec
> > > > > > > > > > >
> > > > > > > > > > > In multi-core vm testing environments, The most significant performance
> > > > > > > > > > > gain is observed in XDP cpumap:
> > > > > > > > > > > Upstream codebase: 1.38 Gbits/sec
> > > > > > > > > > > Upstream codebase + page_pool support: 9.74 Gbits/sec
> > > > > > > > > > >
> > > > > > > > > > > With this foundation, we can further integrate page pool fragmentation and
> > > > > > > > > > > DMA map/unmap support.
> > > > > > > > > > >
> > > > > > > > > > > Signed-off-by: Liang Chen <liangchen.linux@...il.com>
> > > > > > > > > >
> > > > > > > > > > Why off by default?
> > > > > > > > > > I am guessing it sometimes has performance costs too?
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > What happens if we use page pool for big mode too?
> > > > > > > > > > The less modes we have the better...
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > Sure, now I believe it makes sense to enable it by default. When the
> > > > > > > > > packet size is very small, it reduces the likelihood of skb
> > > > > > > > > coalescing. But such cases are rare.
> > > > > > > >
> > > > > > > > small packets are rare? These workloads are easy to create actually.
> > > > > > > > Pls try and include benchmark with small packet size.
> > > > > > > >
> > > > > > >
> > > > > > > Sure, Thanks!
> > > > > >
> > > > > > Before going ahead and posting v2 patch, I would like to hear more
> > > > > > advice for the cases of small packets. I have done more performance
> > > > > > benchmark with small packets since then. Here is a list of iperf
> > > > > > output,
> > > > > >
> > > > > > With PP and PP fragmenting:
> > > > > > 256K: [ 5] 505.00-510.00 sec 1.34 GBytes 2.31 Gbits/sec 0 144 KBytes
> > > > > > 1K: [ 5] 30.00-35.00 sec 4.63 GBytes 7.95 Gbits/sec 0
> > > > > > 223 KBytes
> > > > > > 2K: [ 5] 65.00-70.00 sec 8.33 GBytes 14.3 Gbits/sec 0
> > > > > > 324 KBytes
> > > > > > 4K: [ 5] 30.00-35.00 sec 13.3 GBytes 22.8 Gbits/sec 0
> > > > > > 1.08 MBytes
> > > > > > 8K: [ 5] 50.00-55.00 sec 18.9 GBytes 32.4 Gbits/sec 0
> > > > > > 744 KBytes
> > > > > > 16K: [ 5] 25.00-30.00 sec 24.6 GBytes 42.3 Gbits/sec 0 963 KBytes
> > > > > > 32K: [ 5] 45.00-50.00 sec 29.8 GBytes 51.2 Gbits/sec 0 1.25 MBytes
> > > > > > 64K: [ 5] 35.00-40.00 sec 34.0 GBytes 58.4 Gbits/sec 0 1.70 MBytes
> > > > > > 128K: [ 5] 45.00-50.00 sec 36.7 GBytes 63.1 Gbits/sec 0 4.26 MBytes
> > > > > > 256K: [ 5] 30.00-35.00 sec 40.0 GBytes 68.8 Gbits/sec 0 3.20 MBytes
> > > >
> > > > Note that virtio-net driver is lacking things like BQL and others, so
> > > > it might suffer from buffer bloat for TCP performance. Would you mind
> > > > to measure with e.g using testpmd on the vhost to see the rx PPS?
> > > >
> > >
> > > No problem. Before we proceed to measure with testpmd, could you
> > > please take a look at the PPS measurements we obtained previously and
> > > see if they are sufficient? Though we will only utilize page pool for
> > > xdp on v2.
> > >
> > > netperf -H 192.168.124.197 -p 4444 -t UDP_STREAM -l 0 -- -m $((1))
> > >
> > > with page pool:
> > > 1.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 655092.27 0.35 27508.77 0.03
> > > 0.00 0.00 0.00 0.00
> > > 2.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 654749.87 0.63 27494.42 0.05
> > > 0.00 0.00 0.00 0.00
> > > 3.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 654230.40 0.10 27472.57 0.01
> > > 0.00 0.00 0.00 0.00
> > > 4.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 656661.33 0.15 27574.65 0.01
> > > 0.00 0.00 0.00 0.00
> > >
> > >
> > > without page pool:
> > > 1.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 646515.20 0.47 27148.60 0.04
> > > 0.00 0.00 0.00 0.00
> > > 2.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 653874.13 0.18 27457.61 0.02
> > > 0.00 0.00 0.00 0.00
> > > 3.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 647246.93 0.15 27179.32 0.01
> > > 0.00 0.00 0.00 0.00
> > > 4.
> > > Average: IFACE rxpck/s txpck/s rxkB/s txkB/s
> > > rxcmp/s txcmp/s rxmcst/s %ifutil
> > > Average: enp8s0 650625.07 0.27 27321.18 0.02
> > > 0.00 0.00 0.00 0.00
> > >
> > >
> > > (655092+654749+654230+656661)/(646515+653874+647246+650625) =
> > > 1.00864886500966031113
> > > On average it gives around 0.8% increase in PPS, and this figure can
> > > be reproduced consistently.
> > >
> > > > > >
> > > > > > Without PP:
> > > > > > 256: [ 5] 680.00-685.00 sec 1.57 GBytes 2.69 Gbits/sec 0 359 KBytes
> > > > > > 1K: [ 5] 75.00-80.00 sec 5.47 GBytes 9.40 Gbits/sec 0 730 KBytes
> > > > > > 2K: [ 5] 65.00-70.00 sec 9.46 GBytes 16.2 Gbits/sec 0 1.99 MBytes
> > > > > > 4K: [ 5] 30.00-35.00 sec 14.5 GBytes 25.0 Gbits/sec 0 1.20 MBytes
> > > > > > 8K: [ 5] 45.00-50.00 sec 19.9 GBytes 34.1 Gbits/sec 0 1.72 MBytes
> > > > > > 16K: [ 5] 5.00-10.00 sec 23.8 GBytes 40.9 Gbits/sec 0 2.90 MBytes
> > > > > > 32K: [ 5] 15.00-20.00 sec 28.0 GBytes 48.1 Gbits/sec 0 3.03 MBytes
> > > > > > 64K: [ 5] 60.00-65.00 sec 31.8 GBytes 54.6 Gbits/sec 0 3.05 MBytes
> > > > > > 128K: [ 5] 45.00-50.00 sec 33.0 GBytes 56.6 Gbits/sec 1 3.03 MBytes
> > > > > > 256K: [ 5] 25.00-30.00 sec 34.7 GBytes 59.6 Gbits/sec 0 3.11 MBytes
> > > > > >
> > > > > >
> > > > > > The major factor contributing to the performance drop is the reduction
> > > > > > of skb coalescing. Additionally, without the page pool, small packets
> > > > > > can still benefit from the allocation of 8 continuous pages by
> > > > > > breaking them down into smaller pieces. This effectively reduces the
> > > > > > frequency of page allocation from the buddy system. For instance, the
> > > > > > arrival of 32 1K packets only triggers one alloc_page call. Therefore,
> > > > > > the benefits of using a page pool are limited in such cases.
> > > >
> > > > I wonder if we can improve page pool in this case anyhow.
> > > >
> > >
> > > We would like to make the effort to enhance skb coalecsing to be more
> > > friendly with page pool buffers. But that involves modifications to
> > > some core data structure of mm.
> > >
> > >
> >
> > Just to give an update on the status of v2 progress. We have
> > identified the specific situation where skb coalescing is affected by
> > page pool and small packets. In summary, it was because, in our
> > environment (Fedora 37 default network setup), NetworkManager creates
> > a SOCK_DGRAM socket, which eventually results in skbs being cloned,
> > thus causing the failure of skb coalescing.
> >
> > While it affects small packet performance in our environment, it
> > doesn't necessarily have the same impact for other users.
> > Nevertheless, we are trying to make an optimization to allow skb
> > coalescing in that situation. It may take some time as we are advised
> > to wait for some relevant prior patches to land first.
> > (https://patchwork.kernel.org/project/netdevbpf/patch/20230628121150.47778-1-liangchen.linux@gmail.com/)
>
> If it's not too late, I would like to be copied in the next version of
> this. (Since it seems to be suggested by me).
>
Sure, no problem. It indeed was suggested by you.
Thanks,
Liang
> >
> > In addition, if small packet performance is not dropping anymore,
> > perhaps we can enable page pool for the normal path as well.
>
> It would be simpler if we start from XDP and normal on top. But it's
> your call anyway.
>
> Thanks
>
> >
> >
> > Thanks,
> > Liang
> >
> >
> >
> > > > > In fact,
> > > > > > without page pool fragmenting enabled, it can even hinder performance
> > > > > > from this perspective.
> > > > > >
> > > > > > Upon further consideration, I tend to believe making page pool the
> > > > > > default option may not be appropriate. As you pointed out, we cannot
> > > > > > simply ignore the performance impact on small packets. Any comments on
> > > > > > this will be much appreciated.
> > > > > >
> > > > > >
> > > > > > Thanks,
> > > > > > Liang
> > > > >
> > > > >
> > > > > So, let's only use page pool for XDP then?
> > > >
> > > > +1
> > > >
> > > > We can start from this.
> > > >
> > > > Thanks
> > > >
> > > > >
> > > > > >
> > > > > > > > > The usage of page pool for big mode is being evaluated now. Thanks!
> > > > > > > > >
> > > > > > > > > > > ---
> > > > > > > > > > > drivers/net/virtio_net.c | 188 ++++++++++++++++++++++++++++++---------
> > > > > > > > > > > 1 file changed, 146 insertions(+), 42 deletions(-)
> > > > > > > > > > >
> > > > > > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > > > > > > > > index c5dca0d92e64..99c0ca0c1781 100644
> > > > > > > > > > > --- a/drivers/net/virtio_net.c
> > > > > > > > > > > +++ b/drivers/net/virtio_net.c
> > > > > > > > > > > @@ -31,6 +31,9 @@ module_param(csum, bool, 0444);
> > > > > > > > > > > module_param(gso, bool, 0444);
> > > > > > > > > > > module_param(napi_tx, bool, 0644);
> > > > > > > > > > >
> > > > > > > > > > > +static bool page_pool_enabled;
> > > > > > > > > > > +module_param(page_pool_enabled, bool, 0400);
> > > > > > > > > > > +
> > > > > > > > > > > /* FIXME: MTU in config. */
> > > > > > > > > > > #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
> > > > > > > > > > > #define GOOD_COPY_LEN 128
> > > > > > > > > > > @@ -159,6 +162,9 @@ struct receive_queue {
> > > > > > > > > > > /* Chain pages by the private ptr. */
> > > > > > > > > > > struct page *pages;
> > > > > > > > > > >
> > > > > > > > > > > + /* Page pool */
> > > > > > > > > > > + struct page_pool *page_pool;
> > > > > > > > > > > +
> > > > > > > > > > > /* Average packet length for mergeable receive buffers. */
> > > > > > > > > > > struct ewma_pkt_len mrg_avg_pkt_len;
> > > > > > > > > > >
> > > > > > > > > > > @@ -459,6 +465,14 @@ static struct sk_buff *virtnet_build_skb(void *buf, unsigned int buflen,
> > > > > > > > > > > return skb;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > +static void virtnet_put_page(struct receive_queue *rq, struct page *page)
> > > > > > > > > > > +{
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + page_pool_put_full_page(rq->page_pool, page, true);
> > > > > > > > > > > + else
> > > > > > > > > > > + put_page(page);
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > /* Called from bottom half context */
> > > > > > > > > > > static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > > > > > > > > > struct receive_queue *rq,
> > > > > > > > > > > @@ -555,7 +569,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > > > > > > > > > hdr = skb_vnet_hdr(skb);
> > > > > > > > > > > memcpy(hdr, hdr_p, hdr_len);
> > > > > > > > > > > if (page_to_free)
> > > > > > > > > > > - put_page(page_to_free);
> > > > > > > > > > > + virtnet_put_page(rq, page_to_free);
> > > > > > > > > > >
> > > > > > > > > > > return skb;
> > > > > > > > > > > }
> > > > > > > > > > > @@ -802,7 +816,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> > > > > > > > > > > return ret;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > -static void put_xdp_frags(struct xdp_buff *xdp)
> > > > > > > > > > > +static void put_xdp_frags(struct xdp_buff *xdp, struct receive_queue *rq)
> > > > > > > > > > > {
> > > > > > > > > > > struct skb_shared_info *shinfo;
> > > > > > > > > > > struct page *xdp_page;
> > > > > > > > > > > @@ -812,7 +826,7 @@ static void put_xdp_frags(struct xdp_buff *xdp)
> > > > > > > > > > > shinfo = xdp_get_shared_info_from_buff(xdp);
> > > > > > > > > > > for (i = 0; i < shinfo->nr_frags; i++) {
> > > > > > > > > > > xdp_page = skb_frag_page(&shinfo->frags[i]);
> > > > > > > > > > > - put_page(xdp_page);
> > > > > > > > > > > + virtnet_put_page(rq, xdp_page);
> > > > > > > > > > > }
> > > > > > > > > > > }
> > > > > > > > > > > }
> > > > > > > > > > > @@ -903,7 +917,11 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
> > > > > > > > > > > if (page_off + *len + tailroom > PAGE_SIZE)
> > > > > > > > > > > return NULL;
> > > > > > > > > > >
> > > > > > > > > > > - page = alloc_page(GFP_ATOMIC);
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + page = page_pool_dev_alloc_pages(rq->page_pool);
> > > > > > > > > > > + else
> > > > > > > > > > > + page = alloc_page(GFP_ATOMIC);
> > > > > > > > > > > +
> > > > > > > > > > > if (!page)
> > > > > > > > > > > return NULL;
> > > > > > > > > > >
> > > > > > > > > > > @@ -926,21 +944,24 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
> > > > > > > > > > > * is sending packet larger than the MTU.
> > > > > > > > > > > */
> > > > > > > > > > > if ((page_off + buflen + tailroom) > PAGE_SIZE) {
> > > > > > > > > > > - put_page(p);
> > > > > > > > > > > + virtnet_put_page(rq, p);
> > > > > > > > > > > goto err_buf;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > memcpy(page_address(page) + page_off,
> > > > > > > > > > > page_address(p) + off, buflen);
> > > > > > > > > > > page_off += buflen;
> > > > > > > > > > > - put_page(p);
> > > > > > > > > > > + virtnet_put_page(rq, p);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > /* Headroom does not contribute to packet length */
> > > > > > > > > > > *len = page_off - VIRTIO_XDP_HEADROOM;
> > > > > > > > > > > return page;
> > > > > > > > > > > err_buf:
> > > > > > > > > > > - __free_pages(page, 0);
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + page_pool_put_full_page(rq->page_pool, page, true);
> > > > > > > > > > > + else
> > > > > > > > > > > + __free_pages(page, 0);
> > > > > > > > > > > return NULL;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > @@ -1144,7 +1165,7 @@ static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
> > > > > > > > > > > }
> > > > > > > > > > > stats->bytes += len;
> > > > > > > > > > > page = virt_to_head_page(buf);
> > > > > > > > > > > - put_page(page);
> > > > > > > > > > > + virtnet_put_page(rq, page);
> > > > > > > > > > > }
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > @@ -1264,7 +1285,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
> > > > > > > > > > > cur_frag_size = truesize;
> > > > > > > > > > > xdp_frags_truesz += cur_frag_size;
> > > > > > > > > > > if (unlikely(len > truesize - room || cur_frag_size > PAGE_SIZE)) {
> > > > > > > > > > > - put_page(page);
> > > > > > > > > > > + virtnet_put_page(rq, page);
> > > > > > > > > > > pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
> > > > > > > > > > > dev->name, len, (unsigned long)(truesize - room));
> > > > > > > > > > > dev->stats.rx_length_errors++;
> > > > > > > > > > > @@ -1283,7 +1304,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
> > > > > > > > > > > return 0;
> > > > > > > > > > >
> > > > > > > > > > > err:
> > > > > > > > > > > - put_xdp_frags(xdp);
> > > > > > > > > > > + put_xdp_frags(xdp, rq);
> > > > > > > > > > > return -EINVAL;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > @@ -1344,7 +1365,10 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
> > > > > > > > > > > if (*len + xdp_room > PAGE_SIZE)
> > > > > > > > > > > return NULL;
> > > > > > > > > > >
> > > > > > > > > > > - xdp_page = alloc_page(GFP_ATOMIC);
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + xdp_page = page_pool_dev_alloc_pages(rq->page_pool);
> > > > > > > > > > > + else
> > > > > > > > > > > + xdp_page = alloc_page(GFP_ATOMIC);
> > > > > > > > > > > if (!xdp_page)
> > > > > > > > > > > return NULL;
> > > > > > > > > > >
> > > > > > > > > > > @@ -1354,7 +1378,7 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
> > > > > > > > > > >
> > > > > > > > > > > *frame_sz = PAGE_SIZE;
> > > > > > > > > > >
> > > > > > > > > > > - put_page(*page);
> > > > > > > > > > > + virtnet_put_page(rq, *page);
> > > > > > > > > > >
> > > > > > > > > > > *page = xdp_page;
> > > > > > > > > > >
> > > > > > > > > > > @@ -1400,6 +1424,8 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> > > > > > > > > > > head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
> > > > > > > > > > > if (unlikely(!head_skb))
> > > > > > > > > > > break;
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + skb_mark_for_recycle(head_skb);
> > > > > > > > > > > return head_skb;
> > > > > > > > > > >
> > > > > > > > > > > case XDP_TX:
> > > > > > > > > > > @@ -1410,10 +1436,10 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> > > > > > > > > > > break;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > - put_xdp_frags(&xdp);
> > > > > > > > > > > + put_xdp_frags(&xdp, rq);
> > > > > > > > > > >
> > > > > > > > > > > err_xdp:
> > > > > > > > > > > - put_page(page);
> > > > > > > > > > > + virtnet_put_page(rq, page);
> > > > > > > > > > > mergeable_buf_free(rq, num_buf, dev, stats);
> > > > > > > > > > >
> > > > > > > > > > > stats->xdp_drops++;
> > > > > > > > > > > @@ -1467,6 +1493,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > head_skb = page_to_skb(vi, rq, page, offset, len, truesize, headroom);
> > > > > > > > > > > curr_skb = head_skb;
> > > > > > > > > > >
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + skb_mark_for_recycle(curr_skb);
> > > > > > > > > > > +
> > > > > > > > > > > if (unlikely(!curr_skb))
> > > > > > > > > > > goto err_skb;
> > > > > > > > > > > while (--num_buf) {
> > > > > > > > > > > @@ -1509,6 +1538,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > curr_skb = nskb;
> > > > > > > > > > > head_skb->truesize += nskb->truesize;
> > > > > > > > > > > num_skb_frags = 0;
> > > > > > > > > > > + if (rq->page_pool)
> > > > > > > > > > > + skb_mark_for_recycle(curr_skb);
> > > > > > > > > > > }
> > > > > > > > > > > if (curr_skb != head_skb) {
> > > > > > > > > > > head_skb->data_len += len;
> > > > > > > > > > > @@ -1517,7 +1548,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > }
> > > > > > > > > > > offset = buf - page_address(page);
> > > > > > > > > > > if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
> > > > > > > > > > > - put_page(page);
> > > > > > > > > > > + virtnet_put_page(rq, page);
> > > > > > > > > > > skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
> > > > > > > > > > > len, truesize);
> > > > > > > > > > > } else {
> > > > > > > > > > > @@ -1530,7 +1561,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > > > > > > > > > > return head_skb;
> > > > > > > > > > >
> > > > > > > > > > > err_skb:
> > > > > > > > > > > - put_page(page);
> > > > > > > > > > > + virtnet_put_page(rq, page);
> > > > > > > > > > > mergeable_buf_free(rq, num_buf, dev, stats);
> > > > > > > > > > >
> > > > > > > > > > > err_buf:
> > > > > > > > > > > @@ -1737,31 +1768,40 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
> > > > > > > > > > > * disabled GSO for XDP, it won't be a big issue.
> > > > > > > > > > > */
> > > > > > > > > > > len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);
> > > > > > > > > > > - if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
> > > > > > > > > > > - return -ENOMEM;
> > > > > > > > > > > + if (rq->page_pool) {
> > > > > > > > > > > + struct page *page;
> > > > > > > > > > >
> > > > > > > > > > > - buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
> > > > > > > > > > > - buf += headroom; /* advance address leaving hole at front of pkt */
> > > > > > > > > > > - get_page(alloc_frag->page);
> > > > > > > > > > > - alloc_frag->offset += len + room;
> > > > > > > > > > > - hole = alloc_frag->size - alloc_frag->offset;
> > > > > > > > > > > - if (hole < len + room) {
> > > > > > > > > > > - /* To avoid internal fragmentation, if there is very likely not
> > > > > > > > > > > - * enough space for another buffer, add the remaining space to
> > > > > > > > > > > - * the current buffer.
> > > > > > > > > > > - * XDP core assumes that frame_size of xdp_buff and the length
> > > > > > > > > > > - * of the frag are PAGE_SIZE, so we disable the hole mechanism.
> > > > > > > > > > > - */
> > > > > > > > > > > - if (!headroom)
> > > > > > > > > > > - len += hole;
> > > > > > > > > > > - alloc_frag->offset += hole;
> > > > > > > > > > > - }
> > > > > > > > > > > + page = page_pool_dev_alloc_pages(rq->page_pool);
> > > > > > > > > > > + if (unlikely(!page))
> > > > > > > > > > > + return -ENOMEM;
> > > > > > > > > > > + buf = (char *)page_address(page);
> > > > > > > > > > > + buf += headroom; /* advance address leaving hole at front of pkt */
> > > > > > > > > > > + } else {
> > > > > > > > > > > + if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
> > > > > > > > > > > + return -ENOMEM;
> > > > > > > > > > >
> > > > > > > > > > > + buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
> > > > > > > > > > > + buf += headroom; /* advance address leaving hole at front of pkt */
> > > > > > > > > > > + get_page(alloc_frag->page);
> > > > > > > > > > > + alloc_frag->offset += len + room;
> > > > > > > > > > > + hole = alloc_frag->size - alloc_frag->offset;
> > > > > > > > > > > + if (hole < len + room) {
> > > > > > > > > > > + /* To avoid internal fragmentation, if there is very likely not
> > > > > > > > > > > + * enough space for another buffer, add the remaining space to
> > > > > > > > > > > + * the current buffer.
> > > > > > > > > > > + * XDP core assumes that frame_size of xdp_buff and the length
> > > > > > > > > > > + * of the frag are PAGE_SIZE, so we disable the hole mechanism.
> > > > > > > > > > > + */
> > > > > > > > > > > + if (!headroom)
> > > > > > > > > > > + len += hole;
> > > > > > > > > > > + alloc_frag->offset += hole;
> > > > > > > > > > > + }
> > > > > > > > > > > + }
> > > > > > > > > > > sg_init_one(rq->sg, buf, len);
> > > > > > > > > > > ctx = mergeable_len_to_ctx(len + room, headroom);
> > > > > > > > > > > err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
> > > > > > > > > > > if (err < 0)
> > > > > > > > > > > - put_page(virt_to_head_page(buf));
> > > > > > > > > > > + virtnet_put_page(rq, virt_to_head_page(buf));
> > > > > > > > > > >
> > > > > > > > > > > return err;
> > > > > > > > > > > }
> > > > > > > > > > > @@ -1994,8 +2034,15 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
> > > > > > > > > > > if (err < 0)
> > > > > > > > > > > return err;
> > > > > > > > > > >
> > > > > > > > > > > - err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
> > > > > > > > > > > - MEM_TYPE_PAGE_SHARED, NULL);
> > > > > > > > > > > + if (vi->rq[qp_index].page_pool)
> > > > > > > > > > > + err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
> > > > > > > > > > > + MEM_TYPE_PAGE_POOL,
> > > > > > > > > > > + vi->rq[qp_index].page_pool);
> > > > > > > > > > > + else
> > > > > > > > > > > + err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
> > > > > > > > > > > + MEM_TYPE_PAGE_SHARED,
> > > > > > > > > > > + NULL);
> > > > > > > > > > > +
> > > > > > > > > > > if (err < 0)
> > > > > > > > > > > goto err_xdp_reg_mem_model;
> > > > > > > > > > >
> > > > > > > > > > > @@ -2951,6 +2998,7 @@ static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)
> > > > > > > > > > > ethtool_sprintf(&p, "tx_queue_%u_%s", i,
> > > > > > > > > > > virtnet_sq_stats_desc[j].desc);
> > > > > > > > > > > }
> > > > > > > > > > > + page_pool_ethtool_stats_get_strings(p);
> > > > > > > > > > > break;
> > > > > > > > > > > }
> > > > > > > > > > > }
> > > > > > > > > > > @@ -2962,12 +3010,30 @@ static int virtnet_get_sset_count(struct net_device *dev, int sset)
> > > > > > > > > > > switch (sset) {
> > > > > > > > > > > case ETH_SS_STATS:
> > > > > > > > > > > return vi->curr_queue_pairs * (VIRTNET_RQ_STATS_LEN +
> > > > > > > > > > > - VIRTNET_SQ_STATS_LEN);
> > > > > > > > > > > + VIRTNET_SQ_STATS_LEN +
> > > > > > > > > > > + (page_pool_enabled && vi->mergeable_rx_bufs ?
> > > > > > > > > > > + page_pool_ethtool_stats_get_count() : 0));
> > > > > > > > > > > default:
> > > > > > > > > > > return -EOPNOTSUPP;
> > > > > > > > > > > }
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > +static void virtnet_get_page_pool_stats(struct net_device *dev, u64 *data)
> > > > > > > > > > > +{
> > > > > > > > > > > +#ifdef CONFIG_PAGE_POOL_STATS
> > > > > > > > > > > + struct virtnet_info *vi = netdev_priv(dev);
> > > > > > > > > > > + struct page_pool_stats pp_stats = {};
> > > > > > > > > > > + int i;
> > > > > > > > > > > +
> > > > > > > > > > > + for (i = 0; i < vi->curr_queue_pairs; i++) {
> > > > > > > > > > > + if (!vi->rq[i].page_pool)
> > > > > > > > > > > + continue;
> > > > > > > > > > > + page_pool_get_stats(vi->rq[i].page_pool, &pp_stats);
> > > > > > > > > > > + }
> > > > > > > > > > > + page_pool_ethtool_stats_get(data, &pp_stats);
> > > > > > > > > > > +#endif /* CONFIG_PAGE_POOL_STATS */
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > static void virtnet_get_ethtool_stats(struct net_device *dev,
> > > > > > > > > > > struct ethtool_stats *stats, u64 *data)
> > > > > > > > > > > {
> > > > > > > > > > > @@ -3003,6 +3069,8 @@ static void virtnet_get_ethtool_stats(struct net_device *dev,
> > > > > > > > > > > } while (u64_stats_fetch_retry(&sq->stats.syncp, start));
> > > > > > > > > > > idx += VIRTNET_SQ_STATS_LEN;
> > > > > > > > > > > }
> > > > > > > > > > > +
> > > > > > > > > > > + virtnet_get_page_pool_stats(dev, &data[idx]);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > static void virtnet_get_channels(struct net_device *dev,
> > > > > > > > > > > @@ -3623,6 +3691,8 @@ 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);
> > > > > > > > > > > + if (vi->rq[i].page_pool)
> > > > > > > > > > > + page_pool_destroy(vi->rq[i].page_pool);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > /* We called __netif_napi_del(),
> > > > > > > > > > > @@ -3679,12 +3749,19 @@ static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
> > > > > > > > > > > struct virtnet_info *vi = vq->vdev->priv;
> > > > > > > > > > > int i = vq2rxq(vq);
> > > > > > > > > > >
> > > > > > > > > > > - if (vi->mergeable_rx_bufs)
> > > > > > > > > > > - put_page(virt_to_head_page(buf));
> > > > > > > > > > > - else if (vi->big_packets)
> > > > > > > > > > > + if (vi->mergeable_rx_bufs) {
> > > > > > > > > > > + if (vi->rq[i].page_pool) {
> > > > > > > > > > > + page_pool_put_full_page(vi->rq[i].page_pool,
> > > > > > > > > > > + virt_to_head_page(buf),
> > > > > > > > > > > + true);
> > > > > > > > > > > + } else {
> > > > > > > > > > > + put_page(virt_to_head_page(buf));
> > > > > > > > > > > + }
> > > > > > > > > > > + } else if (vi->big_packets) {
> > > > > > > > > > > give_pages(&vi->rq[i], buf);
> > > > > > > > > > > - else
> > > > > > > > > > > + } else {
> > > > > > > > > > > put_page(virt_to_head_page(buf));
> > > > > > > > > > > + }
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > static void free_unused_bufs(struct virtnet_info *vi)
> > > > > > > > > > > @@ -3718,6 +3795,26 @@ static void virtnet_del_vqs(struct virtnet_info *vi)
> > > > > > > > > > > virtnet_free_queues(vi);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > +static void virtnet_alloc_page_pool(struct receive_queue *rq)
> > > > > > > > > > > +{
> > > > > > > > > > > + struct virtio_device *vdev = rq->vq->vdev;
> > > > > > > > > > > +
> > > > > > > > > > > + struct page_pool_params pp_params = {
> > > > > > > > > > > + .order = 0,
> > > > > > > > > > > + .pool_size = rq->vq->num_max,
> > > > > > > > > > > + .nid = dev_to_node(vdev->dev.parent),
> > > > > > > > > > > + .dev = vdev->dev.parent,
> > > > > > > > > > > + .offset = 0,
> > > > > > > > > > > + };
> > > > > > > > > > > +
> > > > > > > > > > > + rq->page_pool = page_pool_create(&pp_params);
> > > > > > > > > > > + if (IS_ERR(rq->page_pool)) {
> > > > > > > > > > > + dev_warn(&vdev->dev, "page pool creation failed: %ld\n",
> > > > > > > > > > > + PTR_ERR(rq->page_pool));
> > > > > > > > > > > + rq->page_pool = NULL;
> > > > > > > > > > > + }
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > /* How large should a single buffer be so a queue full of these can fit at
> > > > > > > > > > > * least one full packet?
> > > > > > > > > > > * Logic below assumes the mergeable buffer header is used.
> > > > > > > > > > > @@ -3801,6 +3898,13 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
> > > > > > > > > > > vi->rq[i].vq = vqs[rxq2vq(i)];
> > > > > > > > > > > vi->rq[i].min_buf_len = mergeable_min_buf_len(vi, vi->rq[i].vq);
> > > > > > > > > > > vi->sq[i].vq = vqs[txq2vq(i)];
> > > > > > > > > > > +
> > > > > > > > > > > + if (page_pool_enabled && vi->mergeable_rx_bufs)
> > > > > > > > > > > + virtnet_alloc_page_pool(&vi->rq[i]);
> > > > > > > > > > > + else
> > > > > > > > > > > + dev_warn(&vi->vdev->dev,
> > > > > > > > > > > + "page pool only support mergeable mode\n");
> > > > > > > > > > > +
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > /* run here: ret == 0. */
> > > > > > > > > > > --
> > > > > > > > > > > 2.31.1
> > > > > > > > > >
> > > > > > > >
> > > > >
> > > >
> >
>
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