[PATCH net-next] docs: networking: clarify expectation of persistent stats
From: Naveen Mamindlapalli <hidden>
Date: 2025-08-25 13:48:37
Also in:
linux-doc, lkml
Subsystem:
documentation, networking [general], the rest · Maintainers:
Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> --- 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