netdev - [PATCH net-next RFC v1 0/4] veth: reduce reallocations of SKBs when XDP bpf-prog is loaded

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Date: Tue, 22 Aug 2023 19:59:00 +0200
From: Jesper Dangaard Brouer <hawk@...nel.org>
To: netdev@...r.kernel.org, edumazet@...gle.com
Cc: Jesper Dangaard Brouer <hawk@...nel.org>, pabeni@...hat.com,
 kuba@...nel.org, davem@...emloft.net, lorenzo@...nel.org,
 Ilias Apalodimas <ilias.apalodimas@...aro.org>, mtahhan@...hat.com,
 huangjie.albert@...edance.com, Yunsheng Lin <linyunsheng@...wei.com>,
 Liang Chen <liangchen.linux@...il.com>
Subject: [PATCH net-next RFC v1 0/4] veth: reduce reallocations of SKBs when
 XDP bpf-prog is loaded

Loading an XDP bpf-prog on veth device driver results in a significant
performance degradation (for normal unrelated traffic) due to
veth_convert_skb_to_xdp_buff() in most cases fully reallocates an SKB and copy
data over, even when XDP prog does nothing (e.g. XDP_PASS).

This patchset reduce the cases that cause reallocation.
After patchset UDP and AF_XDP sending avoids reallocations.

Future work will investigate TCP.

---

Jesper Dangaard Brouer (4):
      veth: use same bpf_xdp_adjust_head check as generic-XDP
      veth: use generic-XDP functions when dealing with SKBs
      veth: lift skb_head_is_locked restriction for SKB based XDP
      veth: when XDP is loaded increase needed_headroom


 drivers/net/veth.c | 86 +++++++++++++++++++---------------------------
 net/core/dev.c     |  1 +
 net/core/filter.c  |  1 +
 3 files changed, 38 insertions(+), 50 deletions(-)

--
Jesper