1. 25 Jun, 2018 1 commit
    • Florian Westphal's avatar
      xfrm: policy: remove pcpu policy cache · e4db5b61
      Florian Westphal authored
      Kristian Evensen says:
        In a project I am involved in, we are running ipsec (Strongswan) on
        different mt7621-based routers. Each router is configured as an
        initiator and has around ~30 tunnels to different responders (running
        on misc. devices). Before the flow cache was removed (kernel 4.9), we
        got a combined throughput of around 70Mbit/s for all tunnels on one
        router. However, we recently switched to kernel 4.14 (4.14.48), and
        the total throughput is somewhere around 57Mbit/s (best-case). I.e., a
        drop of around 20%. Reverting the flow cache removal restores, as
        expected, performance levels to that of kernel 4.9.
      
      When pcpu xdst exists, it has to be validated first before it can be
      used.
      
      A negative hit thus increases cost vs. no-cache.
      
      As number of tunnels increases, hit rate decreases so this pcpu caching
      isn't a viable strategy.
      
      Furthermore, the xdst cache also needs to run with BH off, so when
      removing this the bh disable/enable pairs can be removed too.
      
      Kristian tested a 4.14.y backport of this change and reported
      increased performance:
      
        In our tests, the throughput reduction has been reduced from around -20%
        to -5%. We also see that the overall throughput is independent of the
        number of tunnels, while before the throughput was reduced as the number
        of tunnels increased.
      Reported-by: default avatarKristian Evensen <kristian.evensen@gmail.com>
      Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
      Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
      e4db5b61
  2. 23 Jun, 2018 25 commits
  3. 22 Jun, 2018 14 commits