On Sun, 29 Apr 2018 11:07:51 -0700 David Ahern <dsah...@gmail.com> wrote:
> Initial performance numbers collected by Jesper, forwarded packets/sec: > > Full stack XDP FIB lookup XDP Direct lookup > IPv4 1,947,969 7,074,156 7,415,333 > IPv6 1,728,000 6,165,504 7,262,720 Do notice these number is single CPU core forwarding performance! On a Broadwell E5-1650 v4 @ 3.60GHz. Another interesting data point is that xdp_redirect_map performance is 13,365,161 pps, which allow us to calculate/isolate the overhead/cost of the FIB lookup. (1/13365161-1/7074156)*10^9 = -66.5 ns (1/13365161-1/7415333)*10^9 = -60.0 ns Which is very close to the measured 50 ns cost of the FIB lookup, done by Vincent Bernat. See: https://vincent.bernat.im/en/blog/2017-ipv4-route-lookup-linux Another way I calculate this is by (ran a new benchmark): Performance: 7641593 (7,641,593) <= tx_unicast /sec * Packet-gap: (1/7641593*10^9) = 130.86 ns Find all FIB related lookup functions in perf-report:: Samples: 93K of event 'cycles:ppp', Event count (approx.): 88553104553 Overhead Cost CPU Command Symbol 20.63 % 26.99 ns 002 ksoftirqd/2 [k] fib_table_lookup 12.92 % 16.90 ns 002 ksoftirqd/2 [k] bpf_fib_lookup 2.40 % 3.14 ns 002 ksoftirqd/2 [k] fib_select_path 0.83 % 1.09 ns 002 ksoftirqd/2 [k] fib_get_table 0.40 % 0.52 ns 002 ksoftirqd/2 [k] l3mdev_fib_table_rcu ----------- Tot:37.18 % (20.63+12.92+2.40+0.83+0.40) =========== Cost of FIB lookup: - 130.86/100*37.18 = 48.65 ns overhead by FIB lookup. Again very close to Vincent's IPv4 measurements of ~50 ns. Notice that the IPv6 measurements does not match up: https://vincent.bernat.im/en/blog/2017-ipv6-route-lookup-linux This is because, we/I'm just testing the IPv6 route cache here... -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
