On Tue, Mar 25, 2025 at 11:18:47AM -0600, Rodrigo Siqueira wrote: > 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. The doc LGTM, thanks! Reviewed-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx> -- An old man doll... just what I always wanted! - Clara
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