CUDA在哪里为堆栈帧分配内核？ [英] Where does CUDA allocate the stack frame for kernels?

问题描述

我的内核调用因内存不足而失败。

My kernel call fails with "out of memory". It makes significant usage of the stack frame and I was wondering if this is the reason for its failure.

当使用--ptxas-options = -v调用nvcc时，它会使用print以下配置文件信息：

When invoking nvcc with --ptxas-options=-v it print the following profile information:

    150352 bytes stack frame, 0 bytes spill stores, 0 bytes spill loads
ptxas info    : Used 59 registers, 40 bytes cmem[0]

硬件：GTX480，sm20,1.5GB设备内存， 48KB共享内存/多处理器。

Hardware: GTX480, sm20, 1.5GB device memory, 48KB shared memory/multiprocessor.

我的问题是堆栈帧的分配：在共享，全局内存，常量内存，..？

My question is where is the stack frame allocated: In shared, global memory, constant memory, ..?

我尝试每个块1个线程，以及每个块32个线程。相同的内存不足。

I tried with 1 thread per block, as well as with 32 threads per block. Same "out of memory".

另一个问题：如果寄存器总数不超过可用的数量，则只能放大驻留在一个多处理器上的线程数寄存器在多处理器（32k为我的卡）。

Another issue: One can only enlarge the number of threads resident to one multiprocessor if the total numbers of registers do not exceed the number of available registers at the multiprocessor (32k for my card). Does something similar apply to the stack frame size?

推荐答案

堆栈分配在本地内存中。分配是每个物理线程（GTX480：15 SM * 1536线程/ SM = 23040线程）。你要求150,352字节/线程=>〜3.4 GB的堆栈空间。如果大小很高，CUDA可以减少每次启动的最大物理线程。

Stack is allocated in local memory. Allocation is per physical thread (GTX480: 15 SM * 1536 threads/SM = 23040 threads). You are requesting 150,352 bytes/thread => ~3.4 GB of stack space. CUDA may reduce the maximum physical threads per launch if the size is that high. The CUDA language is not designed to have a large per thread stack.

在寄存器方面，GTX480每个线程限制为63个寄存器，每个SM限制为32K个寄存器。

In terms of registers GTX480 is limited to 63 registers per thread and 32K registers per SM.

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