Re: [PATCH net-next 2/2] selftests: drv-net: let ethtool stats settle before reading

[David Ahern <dsahern@kernel.org>]

On 8/8/26 10:36 AM, Jakub Kicinski wrote:
> Some devices refresh the statistics exposed via ethtool only
> periodically, every stats-block-usecs (as reported by ethtool -c).
> ethtool_std_stats and ethtool_rmon sample the counters immediately
> after generating traffic, so on such devices they can read stale
> values and fail with a delta short of the packets just sent.
> 
> Add a hw_stats_settle() helper which sleeps for 1.25x the configured
> stats-block-usecs (defaulting to 20ms when the device reports no, or
> a zero, period). Use it for ethtool std stats and RMON.
> The 1.25x/20msec heuristic matches what the Python tests do.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: andrew@lunn.ch
> CC: shuah@kernel.org
> CC: dsahern@kernel.org
> CC: idosch@nvidia.com
> CC: ioana.ciornei@nxp.com
> CC: petrm@nvidia.com
> CC: linux-kselftest@vger.kernel.org
> ---
>  .../selftests/drivers/net/hw/ethtool_rmon.sh      |  2 ++
>  .../selftests/drivers/net/hw/ethtool_std_stats.sh |  2 ++
>  tools/testing/selftests/net/forwarding/lib.sh     | 15 +++++++++++++++
>  3 files changed, 19 insertions(+)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>