 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| • |
Each PCI Express
transaction is issued in one of
|
|
|
eight Traffic
Classes (TC)
|
|
|
|
– |
GPU typically
uses only a few traffic classes
|
|
|
|
– |
Application
software has no direct control over the TC
|
|
|
|
– |
GPU Driver does
have control over the TC
|
|
|
| • |
No ordering is
guaranteed between Traffic Classes
|
|
|
– |
If a GPU
execution unit (3D, MPEG, etc) requires strict ordering
|
|
|
then all ordered
transactions from that unit will be issued in the
|
|
|
same TC
|
|
|
| • |
Each PCI Express
transaction is issued in one of
|
|
|
eight Virtual
Channels (VC)
|
|
|
|
– |
GPUs typically
have no isochronous system requirements
|
|
|
|
– |
GPUs are
typically connected directly to the Root Complex
|
|
|
|
– |
GPU can
efficiently utilize as few as one VC
|
|
