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In-Reply-To: <CAKhg4tJ-=R6Us5hqDOLG2evnvjcFmhunVO1aXtFAvEe3qzH+EQ@mail.gmail.com>
From:   Liang Chen <liangchen.linux@gmail.com>
Date:   Wed, 5 Jul 2023 13:41:02 +0800
Message-ID: <CAKhg4tJd=MdXTYD8bdSwOqdEJ=7Ukvv+13PE4kC96wL+m6-ctA@mail.gmail.com>
Subject: Re: [PATCH net-next 2/5] virtio_net: Add page_pool support to improve performance
To:     Jason Wang <jasowang@redhat.com>
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, xuanzhuo@linux.alibaba.com,
        kuba@kernel.org, edumazet@google.com, davem@davemloft.net,
        pabeni@redhat.com, alexander.duyck@gmail.com
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On Fri, Jun 9, 2023 at 10:57=E2=80=AFAM Liang Chen <liangchen.linux@gmail.c=
om> wrote:
>
> On Thu, Jun 8, 2023 at 8:38=E2=80=AFAM Jason Wang <jasowang@redhat.com> w=
rote:
> >
> > On Thu, Jun 8, 2023 at 4:17=E2=80=AFAM Michael S. Tsirkin <mst@redhat.c=
om> wrote:
> > >
> > > On Wed, Jun 07, 2023 at 05:08:59PM +0800, Liang Chen wrote:
> > > > On Tue, May 30, 2023 at 9:19=E2=80=AFAM Liang Chen <liangchen.linux=
@gmail.com> wrote:
> > > > >
> > > > > On Mon, May 29, 2023 at 5:55=E2=80=AFPM Michael S. Tsirkin <mst@r=
edhat.com> wrote:
> > > > > >
> > > > > > On Mon, May 29, 2023 at 03:27:56PM +0800, Liang Chen wrote:
> > > > > > > On Sun, May 28, 2023 at 2:20=E2=80=AFPM Michael S. Tsirkin <m=
st@redhat.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 pa=
rameter 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 significa=
nt 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@gmail.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. W=
hen 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 actu=
ally.
> > > > > > 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) =3D
> 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 reduct=
ion
> > > > of skb coalescing. Additionally, without the page pool, small packe=
ts
> > > > can still benefit from the allocation of 8 continuous pages by
> > > > breaking them down into smaller pieces. This effectively reduces th=
e
> > > > frequency of page allocation from the buddy system. For instance, t=
he
> > > > arrival of 32 1K packets only triggers one alloc_page call. Therefo=
re,
> > > > 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/)

In addition, if small packet performance is not dropping anymore,
perhaps we can enable page pool for the normal path as well.


Thanks,
Liang


> > > In fact,
> > > > without page pool fragmenting enabled, it can even hinder performan=
ce
> > > > 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 canno=
t
> > > > 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. T=
hanks!
> > > > > > >
> > > > > > > > > ---
> > > > > > > > >  drivers/net/virtio_net.c | 188 +++++++++++++++++++++++++=
+++++---------
> > > > > > > > >  1 file changed, 146 insertions(+), 42 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virti=
o_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 buff=
ers. */
> > > > > > > > >       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, s=
truct 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(st=
ruct virtnet_info *vi,
> > > > > > > > >       hdr =3D 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 ne=
t_device *dev,
> > > > > > > > >       return ret;
> > > > > > > > >  }
> > > > > > > > >
> > > > > > > > > -static void put_xdp_frags(struct xdp_buff *xdp)
> > > > > > > > > +static void put_xdp_frags(struct xdp_buff *xdp, struct r=
eceive_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 =3D xdp_get_shared_info_from_buff(xd=
p);
> > > > > > > > >               for (i =3D 0; i < shinfo->nr_frags; i++) {
> > > > > > > > >                       xdp_page =3D 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_pa=
ge(struct receive_queue *rq,
> > > > > > > > >       if (page_off + *len + tailroom > PAGE_SIZE)
> > > > > > > > >               return NULL;
> > > > > > > > >
> > > > > > > > > -     page =3D alloc_page(GFP_ATOMIC);
> > > > > > > > > +     if (rq->page_pool)
> > > > > > > > > +             page =3D page_pool_dev_alloc_pages(rq->page=
_pool);
> > > > > > > > > +     else
> > > > > > > > > +             page =3D alloc_page(GFP_ATOMIC);
> > > > > > > > > +
> > > > > > > > >       if (!page)
> > > > > > > > >               return NULL;
> > > > > > > > >
> > > > > > > > > @@ -926,21 +944,24 @@ static struct page *xdp_linearize_p=
age(struct receive_queue *rq,
> > > > > > > > >                * is sending packet larger than the MTU.
> > > > > > > > >                */
> > > > > > > > >               if ((page_off + buflen + tailroom) > PAGE_S=
IZE) {
> > > > > > > > > -                     put_page(p);
> > > > > > > > > +                     virtnet_put_page(rq, p);
> > > > > > > > >                       goto err_buf;
> > > > > > > > >               }
> > > > > > > > >
> > > > > > > > >               memcpy(page_address(page) + page_off,
> > > > > > > > >                      page_address(p) + off, buflen);
> > > > > > > > >               page_off +=3D buflen;
> > > > > > > > > -             put_page(p);
> > > > > > > > > +             virtnet_put_page(rq, p);
> > > > > > > > >       }
> > > > > > > > >
> > > > > > > > >       /* Headroom does not contribute to packet length */
> > > > > > > > >       *len =3D 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(stru=
ct receive_queue *rq, int num_buf,
> > > > > > > > >               }
> > > > > > > > >               stats->bytes +=3D len;
> > > > > > > > >               page =3D virt_to_head_page(buf);
> > > > > > > > > -             put_page(page);
> > > > > > > > > +             virtnet_put_page(rq, page);
> > > > > > > > >       }
> > > > > > > > >  }
> > > > > > > > >
> > > > > > > > > @@ -1264,7 +1285,7 @@ static int virtnet_build_xdp_buff_m=
rg(struct net_device *dev,
> > > > > > > > >               cur_frag_size =3D truesize;
> > > > > > > > >               xdp_frags_truesz +=3D cur_frag_size;
> > > > > > > > >               if (unlikely(len > truesize - room || cur_f=
rag_size > PAGE_SIZE)) {
> > > > > > > > > -                     put_page(page);
> > > > > > > > > +                     virtnet_put_page(rq, page);
> > > > > > > > >                       pr_debug("%s: rx error: len %u exce=
eds 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_m=
rg(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 =3D alloc_page(GFP_ATOMIC);
> > > > > > > > > +             if (rq->page_pool)
> > > > > > > > > +                     xdp_page =3D page_pool_dev_alloc_pa=
ges(rq->page_pool);
> > > > > > > > > +             else
> > > > > > > > > +                     xdp_page =3D 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 =3D PAGE_SIZE;
> > > > > > > > >
> > > > > > > > > -     put_page(*page);
> > > > > > > > > +     virtnet_put_page(rq, *page);
> > > > > > > > >
> > > > > > > > >       *page =3D xdp_page;
> > > > > > > > >
> > > > > > > > > @@ -1400,6 +1424,8 @@ static struct sk_buff *receive_merg=
eable_xdp(struct net_device *dev,
> > > > > > > > >               head_skb =3D build_skb_from_xdp_buff(dev, v=
i, &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_me=
rgeable_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_merg=
eable(struct net_device *dev,
> > > > > > > > >       head_skb =3D page_to_skb(vi, rq, page, offset, len,=
 truesize, headroom);
> > > > > > > > >       curr_skb =3D 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_merg=
eable(struct net_device *dev,
> > > > > > > > >                       curr_skb =3D nskb;
> > > > > > > > >                       head_skb->truesize +=3D nskb->trues=
ize;
> > > > > > > > >                       num_skb_frags =3D 0;
> > > > > > > > > +                     if (rq->page_pool)
> > > > > > > > > +                             skb_mark_for_recycle(curr_s=
kb);
> > > > > > > > >               }
> > > > > > > > >               if (curr_skb !=3D head_skb) {
> > > > > > > > >                       head_skb->data_len +=3D len;
> > > > > > > > > @@ -1517,7 +1548,7 @@ static struct sk_buff *receive_merg=
eable(struct net_device *dev,
> > > > > > > > >               }
> > > > > > > > >               offset =3D buf - page_address(page);
> > > > > > > > >               if (skb_can_coalesce(curr_skb, num_skb_frag=
s, 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_merg=
eable(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 =3D get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_=
len, room);
> > > > > > > > > -     if (unlikely(!skb_page_frag_refill(len + room, allo=
c_frag, gfp)))
> > > > > > > > > -             return -ENOMEM;
> > > > > > > > > +     if (rq->page_pool) {
> > > > > > > > > +             struct page *page;
> > > > > > > > >
> > > > > > > > > -     buf =3D (char *)page_address(alloc_frag->page) + al=
loc_frag->offset;
> > > > > > > > > -     buf +=3D headroom; /* advance address leaving hole =
at front of pkt */
> > > > > > > > > -     get_page(alloc_frag->page);
> > > > > > > > > -     alloc_frag->offset +=3D len + room;
> > > > > > > > > -     hole =3D alloc_frag->size - alloc_frag->offset;
> > > > > > > > > -     if (hole < len + room) {
> > > > > > > > > -             /* To avoid internal fragmentation, if ther=
e 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 +=3D hole;
> > > > > > > > > -             alloc_frag->offset +=3D hole;
> > > > > > > > > -     }
> > > > > > > > > +             page =3D page_pool_dev_alloc_pages(rq->page=
_pool);
> > > > > > > > > +             if (unlikely(!page))
> > > > > > > > > +                     return -ENOMEM;
> > > > > > > > > +             buf =3D (char *)page_address(page);
> > > > > > > > > +             buf +=3D headroom; /* advance address leavi=
ng hole at front of pkt */
> > > > > > > > > +     } else {
> > > > > > > > > +             if (unlikely(!skb_page_frag_refill(len + ro=
om, alloc_frag, gfp)))
> > > > > > > > > +                     return -ENOMEM;
> > > > > > > > >
> > > > > > > > > +             buf =3D (char *)page_address(alloc_frag->pa=
ge) + alloc_frag->offset;
> > > > > > > > > +             buf +=3D headroom; /* advance address leavi=
ng hole at front of pkt */
> > > > > > > > > +             get_page(alloc_frag->page);
> > > > > > > > > +             alloc_frag->offset +=3D len + room;
> > > > > > > > > +             hole =3D alloc_frag->size - alloc_frag->off=
set;
> > > > > > > > > +             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 +=3D hole;
> > > > > > > > > +                     alloc_frag->offset +=3D hole;
> > > > > > > > > +             }
> > > > > > > > > +     }
> > > > > > > > >       sg_init_one(rq->sg, buf, len);
> > > > > > > > >       ctx =3D mergeable_len_to_ctx(len + room, headroom);
> > > > > > > > >       err =3D 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_pa=
ir(struct virtnet_info *vi, int qp_index)
> > > > > > > > >       if (err < 0)
> > > > > > > > >               return err;
> > > > > > > > >
> > > > > > > > > -     err =3D xdp_rxq_info_reg_mem_model(&vi->rq[qp_index=
].xdp_rxq,
> > > > > > > > > -                                      MEM_TYPE_PAGE_SHAR=
ED, NULL);
> > > > > > > > > +     if (vi->rq[qp_index].page_pool)
> > > > > > > > > +             err =3D xdp_rxq_info_reg_mem_model(&vi->rq[=
qp_index].xdp_rxq,
> > > > > > > > > +                                              MEM_TYPE_P=
AGE_POOL,
> > > > > > > > > +                                              vi->rq[qp_=
index].page_pool);
> > > > > > > > > +     else
> > > > > > > > > +             err =3D xdp_rxq_info_reg_mem_model(&vi->rq[=
qp_index].xdp_rxq,
> > > > > > > > > +                                              MEM_TYPE_P=
AGE_SHARED,
> > > > > > > > > +                                              NULL);
> > > > > > > > > +
> > > > > > > > >       if (err < 0)
> > > > > > > > >               goto err_xdp_reg_mem_model;
> > > > > > > > >
> > > > > > > > > @@ -2951,6 +2998,7 @@ static void virtnet_get_strings(str=
uct net_device *dev, u32 stringset, u8 *data)
> > > > > > > > >                               ethtool_sprintf(&p, "tx_que=
ue_%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_S=
TATS_LEN +
> > > > > > > > > -                                            VIRTNET_SQ_S=
TATS_LEN);
> > > > > > > > > +                                            VIRTNET_SQ_S=
TATS_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_devic=
e *dev, u64 *data)
> > > > > > > > > +{
> > > > > > > > > +#ifdef CONFIG_PAGE_POOL_STATS
> > > > > > > > > +     struct virtnet_info *vi =3D netdev_priv(dev);
> > > > > > > > > +     struct page_pool_stats pp_stats =3D {};
> > > > > > > > > +     int i;
> > > > > > > > > +
> > > > > > > > > +     for (i =3D 0; i < vi->curr_queue_pairs; i++) {
> > > > > > > > > +             if (!vi->rq[i].page_pool)
> > > > > > > > > +                     continue;
> > > > > > > > > +             page_pool_get_stats(vi->rq[i].page_pool, &p=
p_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_sta=
ts(struct net_device *dev,
> > > > > > > > >               } while (u64_stats_fetch_retry(&sq->stats.s=
yncp, start));
> > > > > > > > >               idx +=3D 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(str=
uct virtnet_info *vi)
> > > > > > > > >       for (i =3D 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_po=
ol);
> > > > > > > > >       }
> > > > > > > > >
> > > > > > > > >       /* We called __netif_napi_del(),
> > > > > > > > > @@ -3679,12 +3749,19 @@ static void virtnet_rq_free_unuse=
d_buf(struct virtqueue *vq, void *buf)
> > > > > > > > >       struct virtnet_info *vi =3D vq->vdev->priv;
> > > > > > > > >       int i =3D 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].p=
age_pool,
> > > > > > > > > +                                             virt_to_hea=
d_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 =3D rq->vq->vdev;
> > > > > > > > > +
> > > > > > > > > +     struct page_pool_params pp_params =3D {
> > > > > > > > > +             .order =3D 0,
> > > > > > > > > +             .pool_size =3D rq->vq->num_max,
> > > > > > > > > +             .nid =3D dev_to_node(vdev->dev.parent),
> > > > > > > > > +             .dev =3D vdev->dev.parent,
> > > > > > > > > +             .offset =3D 0,
> > > > > > > > > +     };
> > > > > > > > > +
> > > > > > > > > +     rq->page_pool =3D page_pool_create(&pp_params);
> > > > > > > > > +     if (IS_ERR(rq->page_pool)) {
> > > > > > > > > +             dev_warn(&vdev->dev, "page pool creation fa=
iled: %ld\n",
> > > > > > > > > +                      PTR_ERR(rq->page_pool));
> > > > > > > > > +             rq->page_pool =3D NULL;
> > > > > > > > > +     }
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > >  /* How large should a single buffer be so a queue full o=
f these can fit at
> > > > > > > > >   * least one full packet?
> > > > > > > > >   * Logic below assumes the mergeable buffer header is us=
ed.
> > > > > > > > > @@ -3801,6 +3898,13 @@ static int virtnet_find_vqs(struct=
 virtnet_info *vi)
> > > > > > > > >               vi->rq[i].vq =3D vqs[rxq2vq(i)];
> > > > > > > > >               vi->rq[i].min_buf_len =3D mergeable_min_buf=
_len(vi, vi->rq[i].vq);
> > > > > > > > >               vi->sq[i].vq =3D vqs[txq2vq(i)];
> > > > > > > > > +
> > > > > > > > > +             if (page_pool_enabled && vi->mergeable_rx_b=
ufs)
> > > > > > > > > +                     virtnet_alloc_page_pool(&vi->rq[i])=
;
> > > > > > > > > +             else
> > > > > > > > > +                     dev_warn(&vi->vdev->dev,
> > > > > > > > > +                              "page pool only support me=
rgeable mode\n");
> > > > > > > > > +
> > > > > > > > >       }
> > > > > > > > >
> > > > > > > > >       /* run here: ret =3D=3D 0. */
> > > > > > > > > --
> > > > > > > > > 2.31.1
> > > > > > > >
> > > > > >
> > >
> >