Hi Maxim, Can you please merge this patch.
Regards, Bala On 1 March 2016 at 08:53, Bill Fischofer <bill.fischo...@linaro.org> wrote: > One small typo noted. Other than that: > > Reviewed-and-tested-by: Bill Fischofer <bill.fischo...@linaro.org> > > > On Mon, Feb 29, 2016 at 7:16 AM, Balasubramanian Manoharan < > bala.manoha...@linaro.org> wrote: > >> User guide documentation for classification >> >> Signed-off-by: Balasubramanian Manoharan <bala.manoha...@linaro.org> >> Reviewed-by: Christophe Milard <christophe.mil...@linaro.org> >> --- >> v6: Incorporates format changes done by Christophe >> v5: Proper documentation for example code >> v4: Adds example code into source code section >> v3: Incorporates classification user guide to main document >> Adds Practical example section >> v2: Incorporates review comments from Christophe >> doc/users-guide/users-guide-cls.adoc | 224 >> +++++++++++++++++++++++++++++++++++ >> doc/users-guide/users-guide.adoc | 2 + >> 2 files changed, 226 insertions(+) >> create mode 100644 doc/users-guide/users-guide-cls.adoc >> >> diff --git a/doc/users-guide/users-guide-cls.adoc >> b/doc/users-guide/users-guide-cls.adoc >> new file mode 100644 >> index 0000000..9e433f2 >> --- /dev/null >> +++ b/doc/users-guide/users-guide-cls.adoc >> @@ -0,0 +1,224 @@ >> +== Classification (CLS) >> + >> +ODP is a framework for software-based packet forwarding/filtering >> applications, >> +and the purpose of the Packet Classification API is to enable >> applications to >> +program the platform hardware or software implementation to assist in >> +prioritization, classification and scheduling of each packet, so that the >> +software application can run faster, scale better and adhere to QoS >> +requirements. >> + >> +The following API abstraction are not modelled after any existing product >> +implementation, but is instead defined in terms of what a typical >> data-plane >> +application may require from such a platform, without sacrificing >> simplicity and >> +avoiding ambiguity. Certain terms that are being used within the context >> of >> +existing products in relation to packet parsing and classification, such >> as >> +access lists are avoided such that not to suggest any relationship >> +between the abstraction used within this API and any particular manner >> in which >> +they may be implemented in hardware. >> + >> +=== Functional Description >> + >> +Following is the functionality that is required of the classification >> API, and >> +its underlying implementation. The details and order of the following >> paragraph >> +is informative, and is only intended to help convey the functional scope >> of a >> +classifier and provide context for the API. In reality, implementations >> may >> +execute many of these steps concurrently, or in different order while >> +maintaining the evident dependencies: >> + >> +1. Apply a set of classification rules to the header of an incoming >> packet, >> +identify the header fields, e.g. ethertype, IP version, IP protocol, >> transport >> +layer port numbers, IP DiffServ, VLAN id, 802.1p priority. >> + >> +2. Store these fields as packet meta data for application use, and for >> the >> +remainder of parser operations. The odp_pktio is also stored as one of >> the meta >> +data fields for subsequent use. >> + >> +3. Compute an odp_cos (Class of Service) value from a subset of >> supported fields >> +from 1) above. >> + >> +4. Based on the odp_cos from 3) above, select the odp_queue through >> which the >> +packet is delivered to the application. >> + >> +5. Validate the packet data integrity (checksums, FCS) and correctness >> (e.g., >> +length fields) and store the validation result, along with optional >> error layer >> +and type indicator, in packet meta data. Optionally, if a packet fails >> +validation, override the odp_cos selection in step 3 to a class of >> service >> +designated for errored packets. >> + >> +6. Based on the odp_cos from 3) above, select the odp_buffer_pool that >> should be >> +used to acquire a buffer to store the packet data and meta data. >> + >> +7. Allocate a buffer from odp_buffer_pool selected in 6) above and >> logically[1] >> +store the packet data and meta data to the allocated buffer, or in >> accordance >> +with class-of-service drop policy and subject to pool buffer >> availability, >> +optionally discard the packet. >> + >> +8. Enqueue the buffer into the odp_queue selected in 4) above. >> + >> +The above is an abstract description of the classifier functionality, >> and may be >> +applied to a variety of applications in many different ways. The ultimate >> +meaning of how this functionality applies to an application also depends >> on >> +other ODP modules, so the above may not complete a full depiction. For >> instance, >> +the exact meaning of priority, which is a per-queue attribute is >> influenced by >> +the ODP scheduler semantics, and the system behavior under stress >> depends on the >> +ODP buffer pool module behavior. >> + >> +For the sole purpose of illustrating the above abstract functionality, >> here is >> +an example of a Layer-2 (IEEE 802.1D) bridge application: Such a >> forwarding >> +application that also adheres to IEEE 802.1p/q priority, which has 8 >> traffic >> +priority levels, might create 8 odp_buffer_pool instances, one for each >> PCP >> +priority level, and 8 odp_queue instances one per priority level. >> Incoming >> +packets will be inspected for a VLAN header; the PCP field will be >> extracted, >> +and used to select both the pool and the queue. Because each queue will >> be >> +assigned a priority value, the packets with highest PCP values will be >> scheduled >> +before any packet with a lower PCP value. Also, in a case of congestion, >> buffer >> +pools for lower priority packets will be depleted earlier than the pools >> +containing packets of the high priority, and hence the lower priority >> packets >> +will be dropped (assuming that is the only flow control method that is >> supported >> +in the platform) while higher priority packets will continue to be >> received into >> +buffers and processed. >> + >> +=== Class of Service Creation and Binding >> + >> +To program the classifier, a class-of-service instance must be created, >> which >> +will contain the packet filtering resources that it may require. All >> subsequent >> +calls refer to one or more of these resources. >> + >> +Each class of service instance must be associated with a single queue or >> queue >> +group, which will be the destination of all packets matching that >> particular >> +filter. The queue assignment is implemented as a separate function call >> such >> +that the queue may be modified at any time, without tearing down the >> filters >> +that define the class of service. In other words, it is possible to >> change the >> +destination queue for a class of service defined by its filters quickly >> and >> +dynamically. >> + >> +Optionally, on platforms that support multiple packet buffer pools, each >> class >> +of service may be assigned a different pool such that when buffers are >> exhausted >> +for one class of service, other classes are not negatively impacted and >> continue >> +to be processed. >> + >> +=== Default packet handling >> + >> +There is a +odp_cos_t+ assigned to each port with the >> +odp_pktio_default_cos_set() function, which will function as the default >> +class-of-service for all packets received from an ingress port, >> +that do not match any of the filters defined subsequently. >> +At minimum this default class-of-service must have a queue and a >> +buffer pool assigned to it on platforms that support multiple packet >> buffer >> +pools. Multiple odp_pktio instances (i.e., multiple ports) may each have >> their >> +own default odp_cos, or may share a odp_cos with other ports, based on >> +application requirements. >> + >> +Packet Classification >> + >> +For each odp_pktio port, the API allows the assignment of a >> class-of-service to >> +a packet using one of three methods: >> + >> +1. The packet may be assigned a specific class-of-service based on its >> Layer-2 >> +(802.1P/902.1Q VLAN tag) priority field. Since the standard field >> defines 8 >> +discrete priority levels, the API allows to assign an odp_cos to each of >> these >> +priority levels with the +odp_cos_with_l2_priority()+ function. >> + >> +2. Similarly, a class-of-service may be assigned using the Layer-3 (IP >> DiffServ) >> +header field. The application supplies an array of odp_cos values that >> covers >> +the entire range of the standard protocol header field, where array >> elements do >> +not need to contain unique values. There is also a need to specify if >> Layer-3 >> +priority takes precedence over Layer-2 priority in a packet with both >> headers >> +present. >> + >> +3. Additionally, the application may also program a number of pattern >> matching >> +rules that assign a class-of-service for packets with header fields >> matching >> +specified values. The field-matching rules take precedence over the >> previously >> +described priority-based assignment of a class-of-service. Using these >> matching >> +rules the application should be able for example to identify all packets >> +containing VoIP traffic based on the protocol being UDP, and a specific >> +destination or source port numbers, and appropriately assign these >> packets a >> +class-of-service that maps to a higher priority queue, assuring voice >> packets a >> +lower and bound latency. >> + >> +Packet meta data Elements >> + >> +Here are the specific information elements that are stored within the >> +packet meta data structure: >> + >> +* Protocol fields that are decoded and extracted by the parsing phase >> + >> +* The pool identifier that is selected for the packet >> + >> +* The ingress port identifier >> + >> +* The result of packet validation, including an indication of the type >> of error >> +detected, if any >> + >> +The ODP packet API module provides accessors for retrieving the above >> meta >> +data fields from the container buffer in an implementation-independent >> manner. >> + >> +=== Example configuration >> + >> +CoS configuration can be best illustrated by drawing a tree, where each >> CoS is >> +the vertex, and each link between any two vertices is a PMR. The root >> node for >> +the tree is the default CoS which is attached with the pktio interface. >> All of >> +the CoS vertices can be final for some packets, if these packets do not >> match >> +any of the link PMRs. >> + >> +.Let us consider the below configuration >> +odp_pktio_default_cos_set(odp_pktio_t pktio, odp_cos_t default_cos); + >> + >> +pmr1 = odp_cls_pmr_create(pmr_match1, default_cos, cos1); + >> +pmr2 = odp_cls_pmr_create(pmr_match2, default_cos, cos2); + >> +pmr3 = odp_cls_pmr_create(pmr_match3, default_cos, cos3); + >> + >> +pmr11 = odp_cls_pmr_create(pmr_match11, cos1, cos11); + >> +pmr12 = odp_cls_pmr_create(pmr_match12, cos1, cos12); + >> + >> +pmr21 = odp_cls_pmr_create(pmr_match11, cos2, cos21); + >> +pmr31 = odp_cls_pmr_create(pmr_match11, cos3, cos31); + >> + >> +The above configuration DOES imply order - a packet that matches >> pmr_match1 will >> +then be applied to pmr_match11 and pmr_match12, and as a result could >> terminate >> +with either cost1, cos11, cos12. In this case the packet was subjected >> to two >> +match attempts in total. >> + >> +The remaining two lines illustrate how a packet that matches pmr_match11 >> could >> +end up wth either cos11, cos21 or cos31, depending on wether it matches >> > > whether > > >> +pmr_march1, pmr_march2 or pmr_match3. >> + >> +=== Practical example >> + >> +Let's look at DNS packets, these are identified by using UDP port 53, >> but each >> +UDP packet may run atop of IPv4 or IPv6, and in turn an IP packet might >> be >> +received as either multicast or unicast, >> + >> +.Very simply, we can create these PMRs >> +PMR-L2 = match all multicast/broadcast packets based on DMAC address + >> +PMR_L3_IP4 = match all IPv4 packets + >> +PMR_L3_IP6 = match all IPv6 packets + >> +PMR_L4_UDP = match all UDP packets + >> +PMR_L4_53 = match all packets with dest port = 53 + >> + >> +[source,c] >> +---- >> +odp_cls_pmr_create(PMR_L2, default_cos, default_cos_mc); >> +odp_cls_pmr_create(PMR_L3_IP4, default_cos, default_cos_ip4_uc); >> +odp_cls_pmr_create(PMR_L3_IP6, default_cos, default_cos_ip6_uc); >> + >> +odp_cls_pmr_create(PMR_L3_IP4, default_cos_mc, default_cos_ip4_mc); >> +odp_cls_pmr_create(PMR_L3_IP6, default_cos_mc, default_cos_ip6_mc); >> +odp_cls_pmr_create(PMR_L4_UDP, default_cos_ip4_uc, cos_udp4_uc); >> +odp_cls_pmr_create(PMR_L4_UDP, default_cos_ip4_mc, cos_udp4_mc); >> +odp_cls_pmr_create(PMR_L4_UDP, default_cos_ip6_uc, cos_udp6_uc); >> +odp_cls_pmr_create(PMR_L4_UDP, default_cos_ip6_mc, cos_udp6_mc); >> + >> +odp_cls_pmr_create(PMR_L4_53, cos_udp4_uc, dns4_uc); >> +odp_cls_pmr_create(PMR_L4_53, cos_udp4_mc, dns4_mc); >> +odp_cls_pmr_create(PMR_L4_53, cos_udp6_uc, dns6_uc); >> +odp_cls_pmr_create(PMR_L4_53, cos_udp6_mc, dns6_mc); >> +---- >> + >> +In this case, a packet may change CoS between 0 and 5 times, meaning >> that up to >> +5 PMRs may be applied in series, and the order >> + >> +Another interesting point is that an implementation will probably impose >> on a >> +limit of how many PMRs can be applied to a packet in series, so in the >> above >> +example, if an implementation limit on the number of consecutive >> classification >> +steps is 4, then all the DNS packets may only reach cos_udp?_?c set of >> vertices. >> diff --git a/doc/users-guide/users-guide.adoc >> b/doc/users-guide/users-guide.adoc >> index ea5e6aa..fc55cea 100644 >> --- a/doc/users-guide/users-guide.adoc >> +++ b/doc/users-guide/users-guide.adoc >> @@ -915,4 +915,6 @@ implementation from the session output pool. >> >> include::users-guide-tm.adoc[] >> >> +include::users-guide-cls.adoc[] >> + >> include::../glossary.adoc[] >> -- >> 1.9.1 >> >> _______________________________________________ >> lng-odp mailing list >> lng-odp@lists.linaro.org >> https://lists.linaro.org/mailman/listinfo/lng-odp >> > >
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