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[net-next,v2,02/15] Documentation: Add description of packet trap policers

Message ID 20200329182119.2207630-3-idosch@idosch.org
State Changes Requested
Delegated to: David Miller
Headers show
Series Add packet trap policers support | expand

Commit Message

Ido Schimmel March 29, 2020, 6:21 p.m. UTC
From: Ido Schimmel <idosch@mellanox.com>

Extend devlink-trap documentation with information about packet trap

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
 .../networking/devlink/devlink-trap.rst       | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
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diff --git a/Documentation/networking/devlink/devlink-trap.rst b/Documentation/networking/devlink/devlink-trap.rst
index 63350e7332ce..a09971c2115c 100644
--- a/Documentation/networking/devlink/devlink-trap.rst
+++ b/Documentation/networking/devlink/devlink-trap.rst
@@ -287,6 +287,32 @@  narrow. The description of these groups must be added to the following table:
      - Contains packet traps for packets that were dropped by the device during
        ACL processing
+Packet Trap Policers
+As previously explained, the underlying device can trap certain packets to the
+CPU for processing. In most cases, the underlying device is capable of handling
+packet rates that are several orders of magnitude higher compared to those that
+can be handled by the CPU.
+Therefore, in order to prevent the underlying device from overwhelming the CPU,
+devices usually include packet trap policers that are able to police the
+trapped packets to rates that can be handled by the CPU.
+The ``devlink-trap`` mechanism allows capable device drivers to register their
+supported packet trap policers with ``devlink``. The device driver can choose
+to associate these policers with supported packet trap groups (see
+:ref:`Generic-Packet-Trap-Groups`) during its initialization, thereby exposing
+its default control plane policy to user space.
+Device drivers should allow user space to change the parameters of the policers
+(e.g., rate, burst size) as well as the association between the policers and
+trap groups by implementing the relevant callbacks.
+If possible, device drivers should implement a callback that allows user space
+to retrieve the number of packets that were dropped by the policer because its
+configured policy was violated.