On Tue, Aug 26, 2025 at 5:49 AM Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx> wrote: > > On Mon, Aug 25, 2025 at 09:53:37PM +0800, Jason Xing wrote: > > From: Jason Xing <kernelxing@xxxxxxxxxxx> > > > > Batch xmit mode needs to allocate and build skbs at one time. To avoid > > reinvent the wheel, use xsk_build_skb() as the second half process of > > the whole initialization of each skb. > > > > The original xsk_build_skb() itself allocates a new skb by calling > > sock_alloc_send_skb whether in copy mode or zerocopy mode. Add a new > > parameter allocated skb to let other callers to pass an already > > allocated skb to support later xmit batch feature. At that time, > > another building skb function will generate a new skb and pass it to > > xsk_build_skb() to finish the rest of building process, like > > initializing structures and copying data. > > are you saying you were able to avoid sock_alloc_send_skb() calls for > batching approach and your socket memory accounting problems disappeared? IIUC, memory accounting is needed because it keeps safe for xsk [1]. The above description says I reused part of xsk_build_skb() in the batching process. [1]: https://lore.kernel.org/all/CAL+tcoBvLHFJJuYawJc3wY2aOrn5CQ3s5+sbC2M24_QNLyBHsg@xxxxxxxxxxxxxx/ > > > > > Signed-off-by: Jason Xing <kernelxing@xxxxxxxxxxx> > > --- > > include/net/xdp_sock.h | 4 ++++ > > net/xdp/xsk.c | 23 ++++++++++++++++------- > > 2 files changed, 20 insertions(+), 7 deletions(-) > > > > diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h > > index c2b05268b8ad..cbba880c27c3 100644 > > --- a/include/net/xdp_sock.h > > +++ b/include/net/xdp_sock.h > > @@ -123,6 +123,10 @@ struct xsk_tx_metadata_ops { > > void (*tmo_request_launch_time)(u64 launch_time, void *priv); > > }; > > > > + > > +struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > > + struct sk_buff *allocated_skb, > > + struct xdp_desc *desc); > > why do you export this? Because patch 5 needs this in xsk_alloc_batch_skb(). Thanks, Jason > > > #ifdef CONFIG_XDP_SOCKETS > > > > int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp); > > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c > > index 173ad49379c3..213d6100e405 100644 > > --- a/net/xdp/xsk.c > > +++ b/net/xdp/xsk.c > > @@ -605,6 +605,7 @@ static void xsk_drop_skb(struct sk_buff *skb) > > } > > > > static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, > > + struct sk_buff *allocated_skb, > > struct xdp_desc *desc) > > { > > struct xsk_buff_pool *pool = xs->pool; > > @@ -618,7 +619,10 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, > > if (!skb) { > > hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(xs->dev->needed_headroom)); > > > > - skb = sock_alloc_send_skb(&xs->sk, hr, 1, &err); > > + if (!allocated_skb) > > + skb = sock_alloc_send_skb(&xs->sk, hr, 1, &err); > > + else > > + skb = allocated_skb; > > if (unlikely(!skb)) > > return ERR_PTR(err); > > > > @@ -657,8 +661,9 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, > > return skb; > > } > > > > -static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > > - struct xdp_desc *desc) > > +struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > > + struct sk_buff *allocated_skb, > > + struct xdp_desc *desc) > > { > > struct xsk_tx_metadata *meta = NULL; > > struct net_device *dev = xs->dev; > > @@ -667,7 +672,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > > int err; > > > > if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) { > > - skb = xsk_build_skb_zerocopy(xs, desc); > > + skb = xsk_build_skb_zerocopy(xs, allocated_skb, desc); > > if (IS_ERR(skb)) { > > err = PTR_ERR(skb); > > goto free_err; > > @@ -683,8 +688,12 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > > first_frag = true; > > > > hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom)); > > - tr = dev->needed_tailroom; > > - skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); > > + if (!allocated_skb) { > > + tr = dev->needed_tailroom; > > + skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); > > + } else { > > + skb = allocated_skb; > > + } > > if (unlikely(!skb)) > > goto free_err; > > > > @@ -818,7 +827,7 @@ static int __xsk_generic_xmit(struct sock *sk) > > goto out; > > } > > > > - skb = xsk_build_skb(xs, &desc); > > + skb = xsk_build_skb(xs, NULL, &desc); > > if (IS_ERR(skb)) { > > err = PTR_ERR(skb); > > if (err != -EOVERFLOW) > > -- > > 2.41.3 > >
