Table of Contents
- 1 Is CUDA shared memory?
- 2 What criterion is used to decide whether a particular global memory access in a kernel is coalesced or not?
- 3 Is shared memory per block?
- 4 What is global memory in computer?
- 5 What is function of global qualifier in CUDA program?
- 6 Is constant memory faster than shared memory?
- 7 What is global memory access and why is it important?
- 8 How do you allocate global memory in C?
Shared memory is a powerful feature for writing well optimized CUDA code. Access to shared memory is much faster than global memory access because it is located on chip. Because shared memory is shared by threads in a thread block, it provides a mechanism for threads to cooperate.
What criterion is used to decide whether a particular global memory access in a kernel is coalesced or not?
The criteria for coalescing are nicely documented in the CUDA 3.2 Programming Guide, Section G. 3.2. The short version is as follows: threads in the warp must be accessing the memory in sequence, and the words being accessed should >=32 bits.
Each block has its own per-block shared memory, which is shared among the threads within that block.
What is pinned memory CUDA?
Pinned Host Memory As you can see in the figure, pinned memory is used as a staging area for transfers from the device to the host. We can avoid the cost of the transfer between pageable and pinned host arrays by directly allocating our host arrays in pinned memory.
What is global memory?
The global memory is defined as the region of system memory that is accessible to both the OpenCL™ host and device. There is a handshake between host and device over control of the data stored in this memory. The host processor transfers data from the host memory space into the global memory space.
What is global memory in computer?
[′glō·bəl ′mem·rē] (computer science) Computer storage that can be used by a number of processors connected together in a multiprocessor system.
What is function of global qualifier in CUDA program?
__global__ : 1. A qualifier added to standard C. This alerts the compiler that a function should be compiled to run on a device (GPU) instead of host (CPU).
Size and Bandwidth Per-block shared memory is faster than global memory and constant memory, but is slower than the per-thread registers.
What kind of memory does a CUDA device use?
There are several kinds of memory on a CUDA device, each with different scope, lifetime, and caching behavior. So far in this series we have used global memory, which resides in device DRAM, for transfers between the host and device as well as for the data input to and output from kernels.
What is the size of the array in CUDA?
Arrays allocated in device memory are aligned to 256-byte memory segments by the CUDA driver. The device can access global memory via 32-, 64-, or 128-byte transactions that are aligned to their size.
What is global memory access and why is it important?
Global memory access on the device shares performance characteristics with data access on the host; namely, that data locality is very important. In early CUDA hardware, memory access alignment was as important as locality across threads, but on recent hardware alignment is not much of a concern.
How do you allocate global memory in C?
Global memory can be declared in global (variable) scope using the __device__ declaration specifier as in the first line of the following code snippet, or dynamically allocated using cudaMalloc () and assigned to a regular C pointer variable as in line 7. Global memory allocations can persist for the lifetime of the application.