From:   Alexander Lobakin <aleksander.lobakin@intel.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>
Cc:     Alexander Lobakin <aleksander.lobakin@intel.com>,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        Larysa Zaremba <larysa.zaremba@intel.com>,
        =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>,
        Song Liu <song@kernel.org>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>, bpf@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH bpf-next v1 0/2] xdp: recycle Page Pool backed skbs built from XDP frames
Date:   Wed,  1 Mar 2023 17:03:13 +0100
Message-Id: <20230301160315.1022488-1-aleksander.lobakin@intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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(-)

-- 
2.39.2