This update clarifies the requirement for preserving statistics across interface up/down cycles, noting that some drivers may not support this due to inherent limitations. It also outlines the potential effects on monitoring and observability tools. Signed-off-by: Naveen Mamindlapalli <naveenm@xxxxxxxxxxx> --- Documentation/networking/statistics.rst | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/Documentation/networking/statistics.rst b/Documentation/networking/statistics.rst index 518284e287b0..857b08d633f7 100644 --- a/Documentation/networking/statistics.rst +++ b/Documentation/networking/statistics.rst @@ -222,8 +222,18 @@ Retrieving ethtool statistics is a multi-syscall process, drivers are advised to keep the number of statistics constant to avoid race conditions with user space trying to read them. -Statistics must persist across routine operations like bringing the interface -down and up. +Statistics are expected to persist across routine operations like bringing the +interface down and up. This includes both standard interface statistics and +driver-defined statistics reported via `ethtool -S`. + +However, this behavior is not always strictly followed, and some drivers do +reset these counters to zero when the device is closed and reopened. This can +lead to misinterpretation of network behavior by monitoring tools, such as +SNMP, that expect monotonically increasing counters. + +Driver authors are expected to preserve statistics across interface down/up +cycles to ensure consistent reporting and better integration with monitoring +tools that consume these statistics. Kernel-internal data structures ------------------------------- -- 2.34.1
