Nvidia Corporation

Cameron Buschardt

Jerome Francis Duluk, Jr

Mark Hairgrove

John Mashey

James Leroy Deming

Brian Matthew Fahs

Lucien Dunning

Chenghuan Jia

Samuel Hammond Duncan

Robert T George

Arvind Gopalakrishnan

Sherry Cheung

Stephen Jones

Vivek Kini

David Fontaine

Piotr Jaroszynski

John Hubbard

James M Van Dyke

Jonathon Stuart Ramsey Evans

Adrian Muntianu

Rajat Agarwal

Yi-Shing Chu (Michael) Chu

The present invention facilitates efficient and effective utilization of unified virtual addresses across multiple components. In one exemplary implementation, an address allocation process comprises: establishing space for managed pointers across a plurality of memories, including allocating one of the managed pointers with a first portion of memory associated with a first one of a plurality of processors; and performing a process of automatically managing accesses to the managed pointers across the plurality of processors and corresponding memories. The automated management can include ensuring consistent information associated with the managed pointers is copied from the first portion of memory to a second portion of memory associated with a second one of the plurality of processors based upon initiation of an accesses to the managed pointers from the second one of the plurality of processors.

Unified memory systems and methods

A system for managing virtual memory. The system includes a first processing unit configured to execute a first operation that references a first virtual memory address. The system also includes a first memory management unit (MMU) associated with the first processing unit and configured to generate a first page fault upon determining that a first page table that is stored in a first memory unit associated with the first processing unit does not include a mapping corresponding to the first virtual memory address. The system further includes a first copy engine associated with the first processing unit. The first copy engine is configured to read a first command queue to determine a first mapping that corresponds to the first virtual memory address and is included in a first page state directory. The first copy engine is also configured to update the first page table to include the first mapping.

Fault buffer for tracking page faults in unified virtual memory system

Techniques are disclosed for tracking memory page accesses in a unified virtual memory system. An access tracking unit detects a memory page access generated by a first processor for accessing a memory page in a memory system of a second processor. The access tracking unit determines whether a cache memory includes an entry for the memory page. If so, then the access tracking unit increments an associated access counter. Otherwise, the access tracking unit attempts to find an unused entry in the cache memory that is available for allocation. If so, then the access tracking unit associates the second entry with the memory page, and sets an access counter associated with the second entry to an initial value. Otherwise, the access tracking unit selects a valid entry in the cache memory; clears an associated valid bit; associates the entry with the memory page; and initializes an associated access counter.

PCIe traffic tracking hardware in a unified virtual memory system

Fault buffer for resolving page faults in unified virtual memory system

One embodiment of the present invention includes a microcontroller coupled to a memory management unit (MMU). The MMU is coupled to a page table included in a physical memory, and the microcontroller is configured to perform one or more virtual memory operations associated with the physical memory and the page table. In operation, the microcontroller receives a page fault generated by the MMU in response to an invalid memory access via a virtual memory address. To remedy such a page fault, the microcontroller performs actions to map the virtual memory address to an appropriate location in the physical memory. By contrast, in prior-art systems, a fault handler would typically remedy the page fault. Advantageously, because the microcontroller executes these tasks locally with respect to the MMU and the physical memory, latency associated with remedying page faults may be decreased. Consequently, overall system performance may be increased.

Microcontroller for memory management unit

Migration scheme for unified virtual memory system

Techniques are provided by which memory pages may be migrated among PPU memories in a multi-PPU system. According to the techniques, a UVM driver determines that a particular memory page should change ownership state and/or be migrated between one PPU memory and another PPU memory. In response to this determination, the UVM driver initiates a peer transition sequence to cause the ownership state and/or location of the memory page to change. Various peer transition sequences involve modifying mappings for one or more PPU, and copying a memory page from one PPU memory to another PPU memory. Several steps in peer transition sequences may be performed in parallel for increased processing speed.

Migration of peer-mapped memory pages

Techniques are disclosed for transitioning a memory page between memories in a virtual memory subsystem. A unified virtual memory (UVM) driver detects a page fault in response to a memory access request associated with a first memory page, where a local page table does not include an entry corresponding to a virtual memory address included in the memory access request. The UVM driver, in response to the page fault, executes a page fault sequence. The page fault sequence includes modifying the ownership state associated with the first memory page to be central-processing-unit-shared. The page fault sequence further includes scheduling the first memory page for migration from a system memory associated with a central processing unit (CPU) to a local memory associated with a parallel processing unit (PPU). One advantage of the disclosed approach is that the PPU accesses memory pages with greater efficiency.

Opportunistic migration of memory pages in a unified virtual memory system

One embodiment of the present invention is a memory subsystem that includes a sliding window tracker that tracks memory accesses associated with a sliding window of memory page groups. When the sliding window tracker detects an access operation associated with a memory page group within the sliding window, the sliding window tracker sets a reference bit that is associated with the memory page group and is included in a reference vector that represents accesses to the memory page groups within the sliding window. Based on the values of the reference bits, the sliding window tracker causes the selection a memory page in a memory page group that has fallen into disuse from a first memory to a second memory. Because the sliding window tracker tunes the memory pages that are resident in the first memory to reflect memory access patterns, the overall performance of the memory subsystem is improved.

Frame buffer access tracking via a sliding window in a unified virtual memory system

Common pointers in unified virtual memory system

PCIE traffic tracking hardware in a unified virtual memory system

Growing community of inventors

Round Rock, TX, United States of America

Cameron Buschardt