netdev - [PATCH bpf-next 0/2] Optimize bpf_redirect_map()/xdp_do

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Date:   Fri, 19 Feb 2021 15:59:20 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        bjorn.topel@...el.com, maciej.fijalkowski@...el.com,
        hawk@...nel.org, toke@...hat.com, magnus.karlsson@...el.com,
        john.fastabend@...il.com, kuba@...nel.org, davem@...emloft.net
Subject: [PATCH bpf-next 0/2] Optimize bpf_redirect_map()/xdp_do_redirect()

Hi XDP-folks,

This two patch series contain two optimizations for the
bpf_redirect_map() helper and the xdp_do_redirect() function.

The bpf_redirect_map() optimization is about avoiding the map lookup
dispatching. Instead of having a switch-statement and selecting the
correct lookup function, we let the verifier patch the
bpf_redirect_map() call to a specific lookup function. This way the
run-time lookup is avoided.

The xdp_do_redirect() patch restructures the code, so that the map
pointer indirection can be avoided.

Performance-wise I got 3% improvement for XSKMAP
(sample:xdpsock/rx-drop), and 4% (sample:xdp_redirect_map) on my
machine.

More details in each commit. Changes since the RFC is outlined in each
commit.

Cheers,
Björn

Björn Töpel (2):
  bpf, xdp: per-map bpf_redirect_map functions for XDP
  bpf, xdp: restructure redirect actions

 include/linux/bpf.h        |  20 ++--
 include/linux/filter.h     |  13 ++-
 include/net/xdp_sock.h     |   6 +-
 include/trace/events/xdp.h |  66 ++++++-----
 kernel/bpf/cpumap.c        |   3 +-
 kernel/bpf/devmap.c        |   5 +-
 kernel/bpf/verifier.c      |  28 +++--
 net/core/filter.c          | 219 ++++++++++++++++++-------------------
 net/xdp/xskmap.c           |   1 -
 9 files changed, 192 insertions(+), 169 deletions(-)

base-commit: 7b1e385c9a488de9291eaaa412146d3972e9dec5
-- 
2.27.0