Abstract: Techniques are provided for restoring threads within a processing core. The techniques include, for a first thread group included in a plurality of thread groups, executing a context restore routine to restore from a memory a first portion of a context associated with the first thread group, determining whether the first thread group completed an assigned function, and, if the first thread group completed the assigned function, then exiting the context restore routine, or if the first thread group did not complete the assigned function, then executing one or more operations associated with a trap handler routine.

Abstract: A technique for controlling the distribution of compute task processing in a multi-threaded system encodes each processing task as task metadata (TMD) stored in memory. The TMD includes work distribution parameters specifying how the processing task should be distributed for processing. Scheduling circuitry selects a task for execution when entries of a work queue for the task have been written. The work distribution parameters may define a number of work queue entries needed before a cooperative thread array” (“CTA”) may be launched to process the work queue entries according to the compute task. The work distribution parameters may define a number of CTAs that are launched to process the same work queue entries. Finally, the work distribution parameters may define a step size that is used to update pointers to the work queue entries.

Abstract: Techniques are provided for restoring threads within a processing core. The techniques include, for a first thread group included in a plurality of thread groups, executing a context restore routine to restore from a memory a first portion of a context associated with the first thread group, determining whether the first thread group completed an assigned function, and, if the first thread group completed the assigned function, then exiting the context restore routine, or if the first thread group did not complete the assigned function, then executing one or more operations associated with a trap handler routine.

Abstract: Techniques are provided for restoring threads within a processing core. The techniques include, for a first thread group included in a plurality of thread groups, executing a context restore routine to restore from a memory a first portion of a context associated with the first thread group, determining whether the first thread group completed an assigned function, and, if the first thread group completed the assigned function, then exiting the context restore routine, or if the first thread group did not complete the assigned function, then executing one or more operations associated with a trap handler routine.

Abstract: One embodiment of the present invention sets forth a technique for instruction level execution preemption. Preempting at the instruction level does not require any draining of the processing pipeline. No new instructions are issued and the context state is unloaded from the processing pipeline. Any in-flight instructions that follow the preemption command in the processing pipeline are captured and stored in a processing task buffer to be reissued when the preempted program is resumed. The processing task buffer is designated as a high priority task to ensure the preempted instructions are reissued before any new instructions for the preempted context when execution of the preempted context is restored.

Abstract: One embodiment of the present invention sets forth a technique for instruction level execution preemption. Preempting at the instruction level does not require any draining of the processing pipeline. No new instructions are issued and the context state is unloaded from the processing pipeline. Any in-flight instructions that follow the preemption command in the processing pipeline are captured and stored in a processing task buffer to be reissued when the preempted program is resumed. The processing task buffer is designated as a high priority task to ensure the preempted instructions are reissued before any new instructions for the preempted context when execution of the preempted context is restored.

Abstract: A texture processing pipeline can be configured to service memory access requests that represent texture data access operations or generic data access operations. When the texture processing pipeline receives a memory access request that represents a texture data access operation, the texture processing pipeline may retrieve texture data based on texture coordinates. When the memory access request represents a generic data access operation, the texture pipeline extracts a virtual address from the memory access request and then retrieves data based on the virtual address. The texture processing pipeline is also configured to cache generic data retrieved on behalf of a group of threads and to then invalidate that generic data when the group of threads exits.

Abstract: One embodiment of the present invention sets forth a technique for selecting a first processor included in a plurality of processors to receive work related to a compute task. The technique involves analyzing state data of each processor in the plurality of processors to identify one or more processors that have already been assigned one compute task and are eligible to receive work related to the one compute task, receiving, from each of the one or more processors identified as eligible, an availability value that indicates the capacity of the processor to receive new work, selecting a first processor to receive work related to the one compute task based on the availability values received from the one or more processors, and issuing, to the first processor via a cooperative thread array (CTA), the work related to the one compute task.

Abstract: One embodiment of the present invention sets forth a technique for mid-primitive execution preemption. When preemption is initiated no new instructions are issued, in-flight instructions progress to an execution unit boundary, and the execution state is unloaded from the processing pipeline. The execution units within the processing pipeline, including the coarse rasterization unit complete execution of in-flight instructions and become idle. However, rasterization of a triangle may be preempted at a coarse raster region boundary. The amount of context state to be stored is reduced because the execution units are idle. Preempting at the mid-primitive level during rasterization reduces the time from when preemption is initiated to when another process can execute because the entire triangle is not rasterized.

Abstract: A texture processing pipeline can be configured to service memory access requests that represent texture data access operations or generic data access operations. When the texture processing pipeline receives a memory access request that represents a texture data access operation, the texture processing pipeline may retrieve texture data based on texture coordinates. When the memory access request represents a generic data access operation, the texture pipeline extracts a virtual address from the memory access request and then retrieves data based on the virtual address. The texture processing pipeline is also configured to cache generic data retrieved on behalf of a group of threads and to then invalidate that generic data when the group of threads exits.

Abstract: A streaming multiprocessor in a parallel processing subsystem processes atomic operations for multiple threads in a multi-threaded architecture. The streaming multiprocessor receives a request from a thread in a thread group to acquire access to a memory location in a lock-protected shared memory, and determines whether a address lock in a plurality of address locks is asserted, where the address lock is associated the memory location. If the address lock is asserted, then the streaming multiprocessor refuses the request. Otherwise, the streaming multiprocessor asserts the address lock, asserts a thread group lock in a plurality of thread group locks, where the thread group lock is associated with the thread group, and grants the request. One advantage of the disclosed techniques is that acquired locks are released when a thread is preempted. As a result, a preempted thread that has previously acquired a lock does not retain the lock indefinitely.

Abstract: One embodiment of the present invention sets forth a technique for instruction level execution preemption. Preempting at the instruction level does not require any draining of the processing pipeline. No new instructions are issued and the context state is unloaded from the processing pipeline. Any in-flight instructions that follow the preemption command in the processing pipeline are captured and stored in a processing task buffer to be reissued when the preempted program is resumed. The processing task buffer is designated as a high priority task to ensure the preempted instructions are reissued before any new instructions for the preempted context when execution of the preempted context is restored.

Abstract: One embodiment of the present invention sets forth a technique for performing nested kernel execution within a parallel processing subsystem. The technique involves enabling a parent thread to launch a nested child grid on the parallel processing subsystem, and enabling the parent thread to perform a thread synchronization barrier on the child grid for proper execution semantics between the parent thread and the child grid. This technique advantageously enables the parallel processing subsystem to perform a richer set of programming constructs, such as conditionally executed and nested operations and externally defined library functions without the additional complexity of CPU involvement.

Abstract: Techniques are provided for restoring threads within a processing core. The techniques include, for a first thread group included in a plurality of thread groups, executing a context restore routine to restore from a memory a first portion of a context associated with the first thread group, determining whether the first thread group completed an assigned function, and, if the first thread group completed the assigned function, then exiting the context restore routine, or if the first thread group did not complete the assigned function, then executing one or more operations associated with a trap handler routine.

Abstract: One embodiment of the present invention sets forth a technique for performing nested kernel execution within a parallel processing subsystem. The technique involves enabling a parent thread to launch a nested child grid on the parallel processing subsystem, and enabling the parent thread to perform a thread synchronization barrier on the child grid for proper execution semantics between the parent thread and the child grid. This technique advantageously enables the parallel processing subsystem to perform a richer set of programming constructs, such as conditionally executed and nested operations and externally defined library functions without the additional complexity of CPU involvement.

Abstract: One embodiment of the present invention sets forth a technique for managing the allocation and release of resources during multi-threaded program execution. Programmable reference counters are initialized to values that limit the amount of resources for allocation to tasks that share the same reference counter. Resource parameters are specified for each task to define the amount of resources allocated for consumption by each array of execution threads that is launched to execute the task. The resource parameters also specify the behavior of the array for acquiring and releasing resources. Finally, during execution of each thread in the array, an exit instruction may be configured to override the release of the resources that were allocated to the array. The resources may then be retained for use by a child task that is generated during execution of a thread.

Abstract: Techniques are provided for restoring thread groups in a cooperative thread array (CTA) within a processing core. Each thread group in the CTA is launched to execute a context restore routine. Each thread group, executes the context restore routine to restore from a memory a first portion of context associated with the thread group, and determines whether the thread group completed an assigned function prior to executing the context restore routine. If the thread group completed an assigned function prior to executing the context restore routine, then the thread group exits the context restore routine. If the thread group did not complete the assigned function prior to executing the context restore routine, then the thread group executes one or more operations associated with a trap handler routine. One advantage of the disclosed techniques is that the trap handling routine operates efficiently in parallel processors.

Abstract: A time slice group (TSG) is a grouping of different streams of work (referred to herein as “channels”) that share the same context information. The set of channels belonging to a TSG are processed in a pre-determined order. However, when a channel stalls while processing, the next channel with independent work can be switched to fully load the parallel processing unit. Importantly, because each channel in the TSG shares the same context information, a context switch operation is not needed when the processing of a particular channel in the TSG stops and the processing of a next channel in the TSG begins. Therefore, multiple independent streams of work are allowed to run concurrently within a single context increasing utilization of parallel processing units.

Abstract: A tag unit configured to manage a cache unit includes a coalescer that implements a set hashing function. The set hashing function maps a virtual address to a particular content-addressable memory unit (CAM). The coalescer implements the set hashing function by splitting the virtual address into upper, middle, and lower portions. The upper portion is further divided into even-indexed bits and odd-indexed bits. The even-indexed bits are reduced to a single bit using a XOR tree, and the odd-indexed are reduced in like fashion. Those single bits are combined with the middle portion of the virtual address to provide a CAM number that identifies a particular CAM. The identified CAM is queried to determine the presence of a tag portion of the virtual address, indicating a cache hit or cache miss.

Abstract: One embodiment of the present invention sets forth a technique for receiving versions of state objects at one or more stages in a processing pipeline. The method includes receiving a first version of a state object at a first stage in the processing pipeline, determining that the first version of the state object is relevant to the first stage, incrementing a first reference counter associated with the first version of the state object, assigning the first version of the state object to work requests that arrive at the first stage subsequent to the receipt of the first version of the state object, and transmitting the first version of the state object to a second stage in the processing pipeline.