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Diffstat (limited to 'Documentation/gpu/amdgpu/gc')
| -rw-r--r-- | Documentation/gpu/amdgpu/gc/index.rst | 52 | ||||
| -rw-r--r-- | Documentation/gpu/amdgpu/gc/mes.rst | 38 |
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diff --git a/Documentation/gpu/amdgpu/gc/index.rst b/Documentation/gpu/amdgpu/gc/index.rst new file mode 100644 index 000000000000..ff6e9ef5cbee --- /dev/null +++ b/Documentation/gpu/amdgpu/gc/index.rst @@ -0,0 +1,52 @@ +.. _amdgpu-gc: + +======================================== + drm/amdgpu - Graphics and Compute (GC) +======================================== + +The relationship between the CPU and GPU can be described as the +producer-consumer problem, where the CPU fills out a buffer with operations +(producer) to be executed by the GPU (consumer). The requested operations in +the buffer are called Command Packets, which can be summarized as a compressed +way of transmitting command information to the graphics controller. + +The component that acts as the front end between the CPU and the GPU is called +the Command Processor (CP). This component is responsible for providing greater +flexibility to the GC since CP makes it possible to program various aspects of +the GPU pipeline. CP also coordinates the communication between the CPU and GPU +via a mechanism named **Ring Buffers**, where the CPU appends information to +the buffer while the GPU removes operations. It is relevant to highlight that a +CPU can add a pointer to the Ring Buffer that points to another region of +memory outside the Ring Buffer, and CP can handle it; this mechanism is called +**Indirect Buffer (IB)**. CP receives and parses the Command Streams (CS), and +writes the operations to the correct hardware blocks. + +Graphics (GFX) and Compute Microcontrollers +------------------------------------------- + +GC is a large block, and as a result, it has multiple firmware associated with +it. Some of them are: + +CP (Command Processor) + The name for the hardware block that encompasses the front end of the + GFX/Compute pipeline. Consists mainly of a bunch of microcontrollers + (PFP, ME, CE, MEC). The firmware that runs on these microcontrollers + provides the driver interface to interact with the GFX/Compute engine. + + MEC (MicroEngine Compute) + This is the microcontroller that controls the compute queues on the + GFX/compute engine. + + MES (MicroEngine Scheduler) + This is the engine for managing queues. For more details check + :ref:`MicroEngine Scheduler (MES) <amdgpu-mes>`. + +RLC (RunList Controller) + This is another microcontroller in the GFX/Compute engine. It handles + power management related functionality within the GFX/Compute engine. + The name is a vestige of old hardware where it was originally added + and doesn't really have much relation to what the engine does now. + +.. toctree:: + + mes.rst diff --git a/Documentation/gpu/amdgpu/gc/mes.rst b/Documentation/gpu/amdgpu/gc/mes.rst new file mode 100644 index 000000000000..b99eb211b179 --- /dev/null +++ b/Documentation/gpu/amdgpu/gc/mes.rst @@ -0,0 +1,38 @@ +.. _amdgpu-mes: + +============================= + MicroEngine Scheduler (MES) +============================= + +.. note:: + Queue and ring buffer are used as a synonymous. + +.. note:: + This section assumes that you are familiar with the concept of Pipes, Queues, and GC. + If not, check :ref:`GFX, Compute, and SDMA Overall Behavior<pipes-and-queues-description>` + and :ref:`drm/amdgpu - Graphics and Compute (GC) <amdgpu-gc>`. + +Every GFX has a pipe component with one or more hardware queues. Pipes can +switch between queues depending on certain conditions, and one of the +components that can request a queue switch to a pipe is the MicroEngine +Scheduler (MES). Whenever the driver is initialized, it creates one MQD per +hardware queue, and then the MQDs are handed to the MES firmware for mapping +to: + +1. Kernel Queues (legacy): This queue is statically mapped to HQDs and never + preempted. Even though this is a legacy feature, it is the current default, and + most existing hardware supports it. When an application submits work to the + kernel driver, it submits all of the application command buffers to the kernel + queues. The CS IOCTL takes the command buffer from the applications and + schedules them on the kernel queue. + +2. User Queues: These queues are dynamically mapped to the HQDs. Regarding the + utilization of User Queues, the userspace application will create its user + queues and submit work directly to its user queues with no need to IOCTL for + each submission and no need to share a single kernel queue. + +In terms of User Queues, MES can dynamically map them to the HQD. If there are +more MQDs than HQDs, the MES firmware will preempt other user queues to make +sure each queues get a time slice; in other words, MES is a microcontroller +that handles the mapping and unmapping of MQDs into HQDs, as well as the +priorities and oversubscription of MQDs. |