Signed-off-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
---
doc/guides/prog_guide/packet_classif_access_ctrl.rst | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/doc/guides/prog_guide/packet_classif_access_ctrl.rst
b/doc/guides/prog_guide/packet_classif_access_ctrl.rst
index 72f4510..e018c68 100644
--- a/doc/guides/prog_guide/packet_classif_access_ctrl.rst
+++ b/doc/guides/prog_guide/packet_classif_access_ctrl.rst
@@ -1,5 +1,5 @@
.. BSD LICENSE
- Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
All rights reserved.
Redistribution and use in source and binary forms, with or without
@@ -51,8 +51,18 @@ The library API provides the following basic operations:
Overview
--------
+Rule definition
+~~~~~~~~~~~~~~~
+
The current implementation allows the user for each AC context to specify its
own rule (set of fields)
over which packet classification will be performed.
+Though there are few restrictions on the rule fields layout:
+
+* First field in the rule definition has to be one byte long.
+* All subsequent fields has to be grouped into sets of 4 consecutive bytes.
+
+This is done mainly for performance reasons - search function processes the
first input byte as part of the flow setup and then the inner loop of the
search function is unrolled to process four input bytes at a time.
+
To define each field inside an AC rule, the following structure is used:
.. code-block:: c
@@ -85,10 +95,7 @@ To define each field inside an AC rule, the following
structure is used:
A zero-based value that represents the position of the field inside the
rule; 0 to N-1 for N fields.
* input_index
- For performance reasons, the inner loop of the search function is unrolled
to process four input bytes at a time.
- This requires the input to be grouped into sets of 4 consecutive bytes.
- The loop processes the first input byte as part of the setup and then
- subsequent bytes must be in groups of 4 consecutive bytes.
+ As mentioned above, all input fields, except the very first one, must be
in groups of 4 consecutive bytes.
The input index specifies to which input group that field belongs to.
* offset
--
1.8.3.1
