[ovs-git] [openvswitch/ovs] 9068a5: dpif-netdev-perf: Fix millisecond stats precision ...

istokes noreply at github.com
Fri Mar 22 22:18:57 UTC 2019


  Branch: refs/heads/branch-2.11
  Home:   https://github.com/openvswitch/ovs
  Commit: 9068a558f5589a32d3e0bc6951772eb57e495214
      https://github.com/openvswitch/ovs/commit/9068a558f5589a32d3e0bc6951772eb57e495214
  Author: Ilya Maximets <i.maximets at samsung.com>
  Date:   2019-03-22 (Fri, 22 Mar 2019)

  Changed paths:
    M lib/dpif-netdev-perf.c

  Log Message:
  -----------
  dpif-netdev-perf: Fix millisecond stats precision with slower TSC.

Unlike x86 where TSC frequency usually matches with CPU frequency,
another architectures could have much slower TSCs.
For example, it's common for Arm SoCs to have 100 MHz TSC by default.
In this case perf module will check for end of current millisecond
each 10K cycles, i.e 10 times per millisecond. This could be not
enough to collect precise statistics.
Fix that by taking current TSC frequency into account instead of
hardcoding the number of cycles.

CC: Jan Scheurich <jan.scheurich at ericsson.com>
Fixes: 79f368756ce8 ("dpif-netdev: Detailed performance stats for PMDs")
Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
Acked-by: Jan Scheurich <jan.scheurich at ericsson.com>
Signed-off-by: Ian Stokes <ian.stokes at intel.com>




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