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f5836ca5e9
There is a need to separate the xdp_redirect tracepoint into two tracepoints, for separating the error case from the normal forward case. Due to the extreme speeds XDP is operating at, loading a tracepoint have a measurable impact. Single core XDP REDIRECT (ethtool tuned rx-usecs 25) can do 13.7 Mpps forwarding, but loading a simple bpf_prog at the tracepoint (with a return 0) reduce perf to 10.2 Mpps (CPU E5-1650 v4 @ 3.60GHz, driver: ixgbe) The overhead of loading a bpf-based tracepoint can be calculated to cost 25 nanosec ((1/13782002-1/10267937)*10^9 = -24.83 ns). Using perf record on the tracepoint event, with a non-matching --filter expression, the overhead is much larger. Performance drops to 8.3 Mpps, cost 48 nanosec ((1/13782002-1/8312497)*10^9 = -47.74)) Having a separate tracepoint for err cases, which should be less frequent, allow running a continuous monitor for errors while not affecting the redirect forward performance (this have also been verified by measurements). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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