[PATCH bpf-next v1 0/2] xdp: recycle Page Pool backed skbs built from XDP frames

Alexander Lobakin
2023-03-01T16:04:20Z

Yeah, I still remember that "Who needs cpumap nowadays" (c), but anyway.

__xdp_build_skb_from_frame() missed the moment when the networking stack
became able to recycle skb pages backed by a Page Pool. This was making
e.g. cpumap redirect even less effective than simple %XDP_PASS. veth was
also affected in some scenarios.
A lot of drivers use skb_mark_for_recycle() already, it's been almost
two years and seems like there are no issues in using it in the generic
code too. {__,}xdp_release_frame() can be then removed as it losts its
last user.
Page Pool becomes then zero-alloc (or almost) in the abovementioned
cases, too. Other memory type models (who needs them at this point)
have no changes.

Some numbers on 1 Xeon Platinum core bombed with 27 Mpps of 64-byte
IPv6 UDP:

Plain %XDP_PASS on baseline, Page Pool driver:

src cpu Rx drops dst cpu Rx
2.1 Mpps N/A 2.1 Mpps

cpumap redirect (w/o leaving its node) on baseline:

6.8 Mpps 5.0 Mpps 1.8 Mpps

cpumap redirect with skb PP recycling:

7.9 Mpps 5.7 Mpps 2.2 Mpps +22%

Alexander Lobakin (2):
xdp: recycle Page Pool backed skbs built from XDP frames
xdp: remove unused {__,}xdp_release_frame()

include/net/xdp.h | 29 -----------------------------
net/core/xdp.c | 19 ++-----------------
2 files changed, 2 insertions(+), 46 deletions(-)

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2.39.2