L- and H-tile Avalon® Streaming and Single Root I/O Virtualization (SR-IOV) Intel® FPGA IP for PCI Express* User Guide

ID 683111
Date 3/07/2022
Public

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4.5. TPH/ATS Capabilities

TLP Processing Hints (TPH) Overview

TPH support PFs that target a TLP towards a specific processing resource such as a host processor or cache hierarchy. Steering Tags (ST) provide design-specific information about the host or cache structure.

Software programs the Steering Tag values that are stored in an ST table. You can store the ST Table in the MSI-X Table or a custom location. For more information about Steering Tags, refer to Section 6.17.2 Steering Tags of the PCI Express Base Specification, Rev. 3.0. After analyzing the traffic of your system, you may be able to use TPH hints to improve latency or reduce traffic congestion.

Address Translation Services (ATS) Overview

ATS extends the PCIe protocol to support an address translation agent (TA) that translates DMA addresses to cached addresses in the device. The translation agent can be located in or above the Root Port. Locating translated addresses in the device minimizes latency and provides a scalable, distributed caching system that improves I/O performance. The Address Translation Cache (ATC) located in the device reduces the processing load on the translation agent, enhancing system performance. For more information about ATS, refer to Address Translation Services Revision 1.1

Table 16.  PF0 - PF4 TPH/ATS

Parameter

Value

Description

Enable Address Translation Services On/Off

When On, the PF supports ATS.

Enable TLP Processing Hints (TPH)

On/Off

When On, the PF supports TPH.

Interrupt Mode

On/Off

When On, an MSI-X interrupt vector number selects the steering tag.

Device Specific Mode

On/Off

When On, the TPH Requestor Capability structure stores the steering tag table.

Steering Tag Table Location

ST table not present

MSI-X table

When On, the MSI-X table stores the steering tag table .

Steering Tag Table size 0-2047 Specifies the number of 2-byte steering table entries.
Table 17.  PF0 - PF4 VF TPH/ATSAll VFs assigned to a PF must have the same settings.

Parameter

Value

Description

Enable Address Translation Services On/Off

When On, the PF supports ATS.

Enable TLP Processing Hints (TPH)

On/Off

When On, the PF supports TPH.

Interrupt Mode

On/Off

When On, an MSI-X interrupt vector number selects the steering tag.

Device Specific Mode

On/Off

When On, the TPH Requestor Capability structure stores the steering tag table.

Steering Tag Table Location

ST table not present

MSI-X table

Selects the location of the steering tag table in Device Specific Mode is On.

Steering Tag Table size 0-2047 Specifies the number of 2-byte steering table entries.