ethdev: introduce shared Rx queue

[dpdk.git] / doc / guides / prog_guide / switch_representation.rst

diff --git a/doc/guides/prog_guide/switch_representation.rst b/doc/guides/prog_guide/switch_representation.rst
index cc1d0d7..4f2532a 100644 (file)
--- a/doc/guides/prog_guide/switch_representation.rst
+++ b/doc/guides/prog_guide/switch_representation.rst
@@ -13,7 +13,7 @@ Introduction
 
 Network adapters with multiple physical ports and/or SR-IOV capabilities
 usually support the offload of traffic steering rules between their virtual
-functions (VFs), physical functions (PFs) and ports.
+functions (VFs), sub functions (SFs), physical functions (PFs) and ports.
 
 Like for standard Ethernet switches, this involves a combination of
 automatic MAC learning and manual configuration. For most purposes it is
@@ -24,7 +24,7 @@ layer 2 (L2) traffic (such as OVS) need to steer traffic themselves
 according on their own criteria.
 
 Without a standard software interface to manage traffic steering rules
-between VFs, PFs and the various physical ports of a given device,
+between VFs, SFs, PFs and the various physical ports of a given device,
 applications cannot take advantage of these offloads; software processing is
 mandatory even for traffic which ends up re-injected into the device it
 originates from.
@@ -34,6 +34,17 @@ the DPDK flow API (**rte_flow**), with emphasis on the SR-IOV use case
 (PF/VF steering) using a single physical port for clarity, however the same
 logic applies to any number of ports without necessarily involving SR-IOV.
 
+Sub Function
+------------
+Besides SR-IOV, Sub function is a portion of the PCI device, a SF netdev
+has its own dedicated queues(txq, rxq). A SF netdev supports E-Switch
+representation offload similar to existing PF and VF representors.
+A SF shares PCI level resources with other SFs and/or with its parent PCI
+function.
+
+Sub function is created on-demand, coexists with VFs. Number of SFs is
+limited by hardware resources.
+
 Port Representors
 -----------------
 
@@ -42,15 +53,16 @@ applications usually have to process a bit of traffic in software before
 thinking about offloading specific flows to hardware.
 
 Applications therefore need the ability to receive and inject traffic to
-various device endpoints (other VFs, PFs or physical ports) before
+various device endpoints (other VFs, SFs, PFs or physical ports) before
 connecting them together. Device drivers must provide means to hook the
 "other end" of these endpoints and to refer them when configuring flow
 rules.
 
 This role is left to so-called "port representors" (also known as "VF
-representors" in the specific context of VFs), which are to DPDK what the
-Ethernet switch device driver model (**switchdev**) [1]_ is to Linux, and
-which can be thought as a software "patch panel" front-end for applications.
+representors" in the specific context of VFs, "SF representors" in the
+specific context of SFs), which are to DPDK what the Ethernet switch
+device driver model (**switchdev**) [1]_ is to Linux, and which can be
+thought as a software "patch panel" front-end for applications.
 
 - DPDK port representors are implemented as additional virtual Ethernet
   device (**ethdev**) instances, spawned on an as needed basis through
@@ -59,9 +71,12 @@ which can be thought as a software "patch panel" front-end for applications.
 
 ::
 
-   -w pci:dbdf,representor=0
-   -w pci:dbdf,representor=[0-3]
-   -w pci:dbdf,representor=[0,5-11]
+   -a pci:dbdf,representor=vf0
+   -a pci:dbdf,representor=vf[0-3]
+   -a pci:dbdf,representor=vf[0,5-11]
+   -a pci:dbdf,representor=sf1
+   -a pci:dbdf,representor=sf[0-1023]
+   -a pci:dbdf,representor=sf[0,2-1023]
 
 - As virtual devices, they may be more limited than their physical
   counterparts, for instance by exposing only a subset of device
@@ -108,6 +123,17 @@ which can be thought as a software "patch panel" front-end for applications.
 .. [1] `Ethernet switch device driver model (switchdev)
        <https://www.kernel.org/doc/Documentation/networking/switchdev.txt>`_
 
+- For some PMDs, memory usage of representors is huge when number of
+  representor grows, mbufs are allocated for each descriptor of Rx queue.
+  Polling large number of ports brings more CPU load, cache miss and
+  latency. Shared Rx queue can be used to share Rx queue between PF and
+  representors among same Rx domain. ``RTE_ETH_DEV_CAPA_RXQ_SHARE`` in
+  device info is used to indicate the capability. Setting non-zero share
+  group in Rx queue configuration to enable share, share_qid is used to
+  identify the shared Rx queue in group. Polling any member port can
+  receive packets of all member ports in the group, port ID is saved in
+  ``mbuf.port``.
+
 Basic SR-IOV
 ------------
 
@@ -360,7 +386,7 @@ Compared to creating a brand new dedicated interface, **rte_flow** was
 deemed flexible enough to manage representor traffic only with minor
 extensions:
 
-- Using physical ports, PF, VF or port representors as targets.
+- Using physical ports, PF, SF, VF or port representors as targets.
 
 - Affecting traffic that is not necessarily addressed to the DPDK port ID a
   flow rule is associated with (e.g. forcing VF traffic redirection to PF).