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Cudamemcpy2d pitch
Cudamemcpy2d pitch. Or, maybe I’m just coding something wrong. where X_h[n*K+k] is the (n,k) element of X_h. When copying a 3D memory chunk, you cannot use cudaMemcpy unless you are copying a single row. I have an existing code that uses Cuda. The problem i have is that i can’t get it to work the results after my kernel execution are just random numbers and not the results as it should be. 1. I am new to using cuda, can someone explain why this is not possible? Using width-1 Nov 11, 2018 · When accessing 2D arrays in CUDA, memory transactions are much faster if each row is properly aligned. h> # include <cuda. Jul 30, 2009 · Update: With reference to above post, the program gives bizarre results when matrix size is increased say 10 * 9 etc . cudaMemcpy2D () returns an error if dpitch or spitch exceeds the maximum allowed. Can you tell or give an example. Jan 2, 2012 · cudaMemcpy2D uses the syntax with dpitch and spitch, but I was not sure, what these values will be when we are copying to host from device. cudaMemcpy2D is designed for copying from pitched, linear memory sources. Mar 7, 2016 · cudaMemcpy2D can only be used for copying pitched linear memory. kind. 2 Oct 3, 2010 · cudaMemcpy2D(copy,Nsizeof(int),matrixD,pitch,Nsizeof(int), M,cudaMemcpyDeviceToHost);[/codebox] When I call cudaMallocPitch it modifies matrixH’s contents. With a width of 100 floats, I would have expected the pitch to be a little more than 400, not 800. I researched the Forum and found out how to copy 2D allocated arrays to the device and vice versa. e. If the program would do it right, it should display 1 but it displays 2010. What I want to do is copy a 2d array A to the device then copy it back to an identical array B. The pitch will be assigned automatically after calling cudaMallocPitch(). Is there any other method to implement this in PVF 13. Jan 9, 2009 · Hello, I want to simulate 2D flows with CUDA (Navier-Stokes-Equations). You should use the step from GpuMat as the source pitch value, or the pitch value from the cudaMalloc3D / cudaMallocPitch call. But I found a workout where I prepare data as 1D array , then use cudamaalocPitch() to place the data in 2D format, do processing and then retrieve data back as 1D array. This worked for me with cudaMemcpy2D. You will need a separate memcpy operation for each pointer held in a1. Does anyone see what I did wrong? - Pitch of destination memory : src - Source memory address : spitch - Pitch of source memory : width - Width of matrix transfer (columns in bytes) height - Height of matrix transfer (rows) kind - Type of transfer Dec 27, 2014 · cudaMemcpy2D参数中pitch的含义 1> pitch的含义 我们知道,对于内存的存取来说,对准偏移量为2的幂(现在一般要求2^4=16)的地址能获取更快的速度,而如果不对齐,可能你需要的数据需要更多的存取次数才能得到。 Feb 3, 2012 · I think that cudaMallocPitch() and cudaMemcpy2D() do not have clear examples in CUDA documentation. h> __global__ void matAdd(float *A_d, float *B_d, size_t pitch_A, size_t pitch_B) { int idx Aug 14, 2010 · Would any of you please mind running or having a look at this code and seeing if it works for you? I’m not even calling a kernel. The pitch returned in the pitch field of pitchedDevPtr is the width in bytes of the allocation. (I just Apr 27, 2016 · cudaMemcpy2D doesn't copy that I expected. Jun 23, 2011 · Hi, This is my code, initializing a matrix d_ref and copying it to device. 1, and also with a stable 3. Jun 27, 2011 · I did some benchmarking on cudamemcpy2d and found that the times were more or less comparable with cudamemcpy. It is an hardware limitation in the copy engine used in cudamemcpy2D. The issue is with host code that tries to pass off a collection of non-contiguous row vectors (or column vectors) as a 2D array. I'm not sure if I'm using cudaMallocPitch and cudaMemcpy2D correctly but I tried to use cudaMemcpy2D and bottom page 20 of CUDA Nov 18, 2011 · When I copy an int 2D array[6][30] into the device memory using cudaMallocPitch and cudamemcpy2D, I have no concept how the compiler pad the row so that it’s best fit for GPU memory transfer. Jun 14, 2017 · I am going to use the grabcutNPP from cuda sample in order to speed up the image processing. Mar 25, 2008 · I had a quick question about cudaMemcpy2D. Jul 9, 2008 · #include <stdio. png (that was decoded) as an input but now I For allocations of 2D arrays, it is recommended that programmers consider performing pitch allocations using cudaMallocPitch(). FROMPRINCIPLESTOPRACTICE:ANALYSISANDTUNINGROOFLINE ANALYSIS Intensity (flop:byte) Gflop/s 16 32 64 128 256 512 12 48 16 32 64128256512 Platform Fermi C1060 Nehalem x 2 Dec 6, 2022 · I am new to cuda and still trying to figure things out, so this question maybe dumb but I can't seem to figure out the problem so bare with me. You have made a mistake in how you are using the call but you haven't provided enough information to tell what is wrong. The relevant CUDA Jul 9, 2009 · UPDATE: I fixed it. cudaMemcpy2D是用于2D线性存储器的数据拷贝,函数原型为: cudaMemcpy2D( void* dst,size_t dpitch,const void* src,size_t spitch,size_t width,size_t height,enum cudaMemcpyKind kind ) 这里需要特别注意width与pitch的区别,width是实际需要拷贝的数据宽度而pitch是2D线性存储空间分配时对齐 Nov 11, 2009 · direct to the question i need to copy 4 2d arrays to gpu, i use cudaMallocPitch and cudaMemcpy2D to accelerate its speed, but it turns out there are problems i can not figure out the code segment is as follows: int valid_dim[][NUM_USED_DIM]; int test_data_dim[][NUM_USED_DIM]; int *g_valid_dim; int *g_test_dim; //what i should say is the variable with a prefix g_ shows that it is on the gpu Dec 7, 2009 · I tried a very simple CUDA program in order to learn the function API cudaMemcpy2D(); Here below is my src code, the result shows is not correct for the computing the matrix operation for A = B + C; #include <stdio. Not the same thing. You must use any other kind of copy utility provided by the CUDA utility that takes the pitch into account. memory pitch Oct 20, 2010 · Hi, I wanted to copy a 2D array from the CPU to the GPU and than back to the CPU. Recently it worked with . Jul 7, 2009 · This is the code iam runing , i have used cudamemcpy2d to copy 2d array from Device to Host, and when I print it, It shows garbage, Can any body guide me . You can use cudaMemcpy2D to copy to a destination buffer where dpitch=width cudaMemcpy2D does not need any particular pitch values (does not need pitch values that are multiples of Oct 28, 2011 · In the CUDA toolkit reference manual you can see that the pitch in the cudaMallocPitch is the allocated width in bytes for the 2D array you are copying. In cudaMallocPitch the returned pitch is for bytes. Since I am having some trouble, I developed a simple kernel, which copy a matrix into another. The function determines the best pitch and returns it to the Jan 28, 2020 · As pointed out in a previous answer, when performing 2D memory copy of OpenCV Mat to device memory allocated using cudaMallocPitch ( or any strided 2D memory), we have to use the step member of the OpenCV Mat to specify the alignment of each row. What am i doing wrong using 2D arrays, hope that someone can help me with this? My Jun 1, 2022 · None of the limitations you are imagining are true, from my perspective. numbers = (float*)malloc(sizeof(float) * pitch * height); And your float **d_numbers must be a typo, for this to work you want float *d_numbers. I found that in the books they use cudaMemCpy2D to implement this. float X Jun 8, 2012 · The 2D matrix on the host appears to be a collection of independently allocated rows, plus a vector of pointers datoin->prec_ini, each element of which points to the start of one row. Jun 20, 2012 · Greetings, I’m having some trouble to understand if I got something wrong in my programming or if there’s an unclear issue (to me) on copying 2D data between host and device. Here it is the code: [codebox]global void matrixCopy(float* a, float* c, int a_pitch, int c_pitch, int width) { int x = blockIdx. But cudaMemcpy2D it has many input parameters that are obscure to interpret in this context, such as pitch. If you are making a CP from host to device then what do you use for the source pitch since it was not allocated with cudaMallocPitch? [snapback]350736[/snapback] The data width. x*blockDim. 6. Your source array is not pitched linear memory, it is an array of pointers. 8k次,点赞5次,收藏26次。文章详细介绍了如何使用CUDA的cudaMemcpy函数来传递一维和二维数组到设备端进行计算,包括内存分配、数据传输、核函数的执行以及结果回传。 Sep 23, 2014 · If this sort of question has been asked I apologize, link me to the thread please! Anyhow I am new to CUDA (I'm coming from OpenCL) and wanted to try generating an image with it. y*blockDim. I said “despite the naming”. x + threadIdx. then copies the image ‘dstImg’ to an image ‘dstImgCpu’ (which has its buffer in CPU memory). h> global void multi( double *M1, s… Jul 30, 2015 · Since this is a pet peeve of mine: cudaMemcpy2D() is appropriately named in that it deals with 2D arrays. [/b] and is it the best way of doing this job? Thanks in advance. So when addressing you should go for the byte address or you can divide the pitch by the size of dataType and when doing mem-copies you multiply the pitch by size of dataType and everything will align correctly. nvidia. The simplest approach (I think) is to "flatten" the 2D arrays, both on host and device, and use index arithmetic to simulate 2D coordinates: Jun 4, 2019 · (As you can see, the pitch at the source is effectively zero, while the pitch at the destination is dest_pitch-- maybe that helps?) An additional hassle is that I do not allocate the data that needs to be transferred myself and so I cannot apply the pitch manually without creating an additional copy of the data (which would be problematic). cudaMemcpy2D()和cudaMallocPitch()的使用,代码先锋网,一个为软件开发程序员提供代码片段和技术文章聚合的网站。 dst - Destination memory address : dpitch - Pitch of destination memory : src - Source memory address : spitch - Pitch of source memory : width - Width of matrix transfer (columns in bytes) Copies count bytes from the memory area pointed to by src to the memory area pointed to by dst, where kind is one of cudaMemcpyHostToHost, cudaMemcpyHostToDevice, cudaMemcpyDeviceToHost, or cudaMemcpyDeviceToDevice, and specifies the direction of the copy. h> #include <stdlib. Note that this function may also return error codes from previous, asynchronous launches. Apr 7, 2009 · Yes, the limitation still holds. h> global void test(int *p, size_t pitch){ *((int *)((char *)p + threadIdx. Here is the example code (running in my machine): #include <iostream> using dst - Destination memory address : dpitch - Pitch of destination memory : src - Source memory address : spitch - Pitch of source memory : width - Width of matrix transfer (columns in bytes) Pitch 是一行所占的字节数, 先将指针N 强制转化为char*(char 占1Byte,float占3Byte), 在向后移动Pitch个字节,得到(char*)N+1*Pitch ,它是第1行(从0计数)的首地址;再将它转换回float*,就可以通过这个指针(row) 来访问第1行。 Feb 1, 2012 · Hi, I was looking through the programming tutorial and best practices guide. x * pitch) + threadIdx. After I read the manual about cudaMallocPitch, I try to make some code to understand what's going on. I’m not an expert on OpenCV, but if you want to concoct a (complete) CUDA example that doesn’t use OpenCV, I’m sure we can sort it out . Jul 30, 2015 · Hi, I’m currentyly trying to pass a 2d array to cuda with CudaMalloc pitch and CudaMemcpy2D. cudaMallocPitch、cudaMemcpy2Dについて、pitchとwidthが引数としてある点がcudaMallocなどとの違いか。 Aug 28, 2012 · I am trying to implement Sauvola Binarization in cuda. The third call is actually OK since it's going in the opposite direction, the source and destination matrices are swapped, so they line up with your pitch parameters Jun 18, 2014 · As mentioned in title, I found that the function of cudaMallocPitch() consumes a lot of time and cudaMemcpy2D() consumes quite some time as well. y Aug 9, 2022 · CUDA関数は、引数が多くて煩雑で、使うのが大変だ(例えばcudaMemcpy2D) そこで、以下のコードを作ったら、メモリ管理が楽になった Dec 9, 2011 · This is my code, initializing a matrix d_ref and copying it to device. Most of the way I learned more complex problems was to create or find examples like this and slowly convert it to my application. May 17, 2011 · In this line of your code: cudaMemcpy2D(devPtr,pitch,testarray,0,8* sizeof(int),4,cudaMemcpyHostToDevice); you're saying the source-pitch value for testarray is equal to 0, but how can that be possible when the formula for pitch is T* elem = (T*)((char*)base_address + row * pitch) + column? enum cudaMemcpyKind. How to use this API to implement this. It seems that cudaMemcpy2D refuses to copy data to a destination which has dpitch = width. Thanks #include <stdio. プログラムの内容. Aug 17, 2014 · Hello! I want to implement copy from device array to device array in the host code in CUDA Fortran by PVF 13. Calling cudaMemcpy2D () with dst and src pointers that do not match the direction of the copy results in an undefined behavior. I will write down more details to explain about them later on. The pitch value returned by that function is a value in bytes. You cannot sensibly use that as a loop index for matrix multiplication. If for some reason you must use the collection-of-vectors storage scheme on the host, you will need to copy each individual vector with a separate cudaMemcpy* (). This is working for all sizes. Do I have to insert a ‘cudaDeviceSynchronize’ before the ‘cudaMemcpy2D’ in Nov 13, 2009 · I feel kind of silly asking this question but I can’t get cudaMemcpy2D to work. I tried to use cudaMemcpy2D because it allows a copy with different pitch: in my case, destination has dpitch = width, but the source spitch > width. How many int elements to pad at the end of my 30 int elements? I thought 30 int takes 120 byte, so another 2 padding needed to pad the chunk to a 128 byte which is a memory transaction size, but Practice code for CUDA image processing. Following code should be the shortest to demonstrate problem: #include<stdio. I’m using cudaMallocPitch() to allocate memory on device side. The May 8, 2012 · The pitch is in bytes, not in the number of elements, because cudaMallocPitch() has no idea what you intend to use the memory for and thus doesn’t know the element size to divide by. Dec 8, 2008 · I have some problems using 2D arrays in CUDA i’m currently reading some resources from file into a 2D array (dimensions of my array [32][1000] doubles). I think the code below is a good starting point to understand what these functions do. You'll note that it expects single pointers (*) to be passed to it, not double pointers (**). I’m struggling with this one and am beginning to think that my implementation must be buggy or unstable. pitch = width + padding; In this case, padding is 0. The original sample code is implemented for FIBITMAP, but my input/output type will be Mat. cirus July 29, 2009, 4:47pm . There is no “deep” copy function for copying arrays of pointers and what they point to in the API. I am merely saying that anybody who thinks “2D” in the name of this function implies collection-of-vectors storage is wide off the mark, and through no fault of the engineer who decided on the name of this API call (no, it wasn’t me :-) Maybe someone can pinpoint the (text)book that lead to a conflation of 2D Jun 14, 2019 · Intuitively, cudaMemcpy2D should be able to do the job, because "strided elements can be see as a column in a larger array". I am trying to allocate memory for image size 1366x768 using CudaMallocPitch and transferring data to Device using cudaMemcpy2D/ cudaMalloc . May 16, 2011 · You can use cudaMemcpy2D for moving around sub-blocks which are part of larger pitched linear memory allocations. Contribute to z-wony/CudaPractice development by creating an account on GitHub. For this I have read the image in a 2d array in host and allocating memory for 2D array in device using pitch. Here is the code I am using: cudaMallocPitch((voi May 3, 2014 · I'm new to cuda and C++ and just can't seem to figure this out. Can anyone please tell me reason for that. When using cudaMalloc3D, you receive a pitch value that you must carefully keep for subsequent access to the memory. This is how I allocate the memory for the array in the device and copy the matrix: int *d_A; size_t pitch; cudaMallocPitch((void**)&d_A, &pitch, sizeof(int)*cols, rows); cudaMemcpy2D(d_A, pitch, A, sizeof(int)*cols, sizeof(int)*cols, rows, cudaMemcpyHostToDevice); where cols Nov 16, 2009 · I have a question about cudaMallocPitch() and cudaMemcpy2D(). Q1. Can anyone tell me the reason behind this seemingly arbitrary limit? As far as I understood, having a pitch for a 2D array just means making sure the rows are the right size so that alignment is the same for every row and you still get coalesced memory access. I try to assign 32 to pitch when calling cudaMemcpy2D() . x * blockDim. Jul 30, 2013 · Despite it's name, cudaMemcpy2D does not copy a doubly-subscripted C host array (**) to a doubly-subscripted (**) device array. float X_h; X_h = (float )malloc(NKsizeof(float));. If you are 100% sure each element is processed you do not even need a memory set operation, the allocation is just enough, since you write the output of every element. CUDA Toolkit v12. com Jul 30, 2015 · So, if at all possible, use contiguous storage (possibly with row or column padding) for 2D matrices in both host and device code. I am not sure who popularized this storage organization, but I consider it harmful to any code that wants to deal with matrices efficiently Aug 22, 2016 · I have a code like myKernel<<<…>>>(srcImg, dstImg) cudaMemcpy2D(…, cudaMemcpyDeviceToHost) where the CUDA kernel computes an image ‘dstImg’ (dstImg has its buffer in GPU memory) and the cudaMemcpy2D fn. These are two functions that I wrote to work around the issue, they are for double precision data but it is very simple to convert them to float: 44 3. Jan 20, 2020 · I am new to C++ (aswell as Cuda and OpenCV), so I am sorry for any mistakes on my side. Mar 6, 2013 · Ive made the following changes and i still get a seg fault: err = cudaMemcpy2D(color,100*3,d_color,pitch,3 *sizeof(unsigned char),3, cudaMemcpyDeviceToHost); Aug 18, 2009 · I’m posting problem-code back down: [codebox] int *neuronxy_cuda; size_t pitch_neuronxy_cuda; //pitch è la larghezza in byte per ogni riga cudaMallocPitch((void Nov 16, 2009 · I have a question about cudaMallocPitch() and cudaMemcpy2D(). x * pitch + threadIdx. Weird things are happening here on x86_64 in linux newest 3. But it is giving me segmentation fault. 0. 9. May 23, 2017 · Hi, I tried to accelerate an image processing function using Pitch, but I have really bad performance. For the most part, cudaMemcpy (including cudaMemcpy2D) expect an ordinary pointer for source and destination, not a pointer-to-pointer. __host__ float *d_ref; float **h_ref = new float* [width]; for (int i=0;i<width;i++) h_ref[i]= new float [height Apr 21, 2009 · Hello to All, I am trying to make some matrix computation, and I am using cudaMemcpy2D and cudaMallocPitch. I have searched C/src/ directory for examples, but cannot find any. y) = 1; } # define X 30 # define Dec 20, 2011 · If you want to move only 0’s to the device you do not need a memory copy operation, you need a memory set operation, which is much faster. - Pitch of source memory : width - Width of matrix transfer (columns in bytes) height cudaMemcpy, cudaMemcpy2D, cudaMemcpyToArray, cudaMemcpy2DToArray, Oct 30, 2020 · So it turns out that copying cv::GpuMat with cudaMemcpy2D works ok. Thanks, Tushar Jul 7, 2010 · Hi Sabkalyan, Thanks for ur reply. Pitch is a good technique to speedup memory access. I want to check if the copied data using cudaMemcpy2D() is actually there. For example, I manager to use cudaMemcpy2D to reproduce the case where both strides are 1. But, well, I got a problem. For allocations of 2D arrays, it is recommended that programmers consider performing pitch allocations using cudaMallocPitch(). y)=123; } main(){ int *p, p_h[5][5], i Jul 30, 2015 · I did not mean to imply that you consider cudaMemcpy2D inappropriately named. The operations seem Aug 6, 2009 · You should know the pitch from the way you allocated numbers. Nightwish - Pitch of source memory : width - Width of matrix transfer (columns in bytes) height cudaMemcpy, cudaMemcpy2D, cudaMemcpyToArray, cudaMemcpy2DToArray, Jul 29, 2009 · CUDA Programming and Performance. float *numbers. I wanted to know if there is a clear example of this function and if it is necessary to use this function in Feb 21, 2013 · There are lots of problems in this code, including but not limited to using array sizes in bytes and word sizes interchangeably in several places in code, using incorrect types (note that size_t exists for a very good reason) , potential truncation and type casting problems, and more. There is a very brief mention of cudaMemcpy2D and it is not explained completely. It was interesting to find that using cudamalloc and cudamemcpy vice cudamallocpitch and cudamemcpy2d for a matrix addition kernel I wrote was faster. I would expect that the B array would Jun 9, 2008 · I use the “cudaMemcpy2D” function as follow : cudaMemcpy2D(A, pA, B, pB, width_in_bytes, height, cudaMemcpyHostToDevice); As I know that B is an host float*, I have pB=width_in_bytes=N*sizeof(float). Under the above hypotheses (single precision 2D matrix), the syntax is the following: cudaMemcpy2D(devPtr, devPitch, hostPtr, hostPitch, Ncols * sizeof(float), Nrows, cudaMemcpyHostToDevice) where See full list on developer. h> #include <cuda. Nov 16, 2010 · #include <stdio. Do you have any idea ? Here is the host part: //image size int Jan 7, 2015 · Hi, I am new to Cuda Programming. There is no obvious reason why there should be a size limit. in followinf Figure 2, so that 2D copy could work for gazilions of bodies even with the. and all the replies I’ve seen to other people boil down to “Manage the pitch yourself, a 2D array is just compiler syntax sugar”. h> #include <cuda_runtime. float X_d;. The only value i get is pointer and i don’t understand why? This is an exemple of my code: double** busdata; double** lineda… Mar 20, 2011 · No it isn’t. Aug 29, 2024 · Search In: Entire Site Just This Document clear search search. Destination pitch should be the width of the image (because there is no additional spacing in a continuous image). リニアメモリとCUDA配列. x; int y = blockIdx. May 30, 2015 · I always thought that if a picture was worth a thousand words a short compileable example focused on the topic must be worth two thousand. There is no problem in doing that. Aug 18, 2020 · 关于cuda并行计算,我之前正儿八经的写过两篇博客: 【遇见cuda】线程模型与内存模型 【遇见cuda】cuda算法效率提升关键点概述. [b]The problem I had is solved. Sep 28, 2014 · Good day, I am learning CUDA at the moment, and I am trying to use a kernel that modifies the elements of a 2d matrix. x; int yid Mar 7, 2022 · 2次元画像においては、cudaMallocPitchとcudaMemcpy2Dが推奨されているようだ。これらを用いたプログラムを作成した。 参考サイト. 9? Thanks in advance. h> __global__ void test(int *p, size_t pitch){ *((char *)p + threadIdx. CUDA Runtime API dst - Destination memory address : dpitch - Pitch of destination memory : src - Source memory address : spitch - Pitch of source memory : width - Width of matrix transfer (columns in bytes) Aug 20, 2007 · cudaMemcpy2D() fails with a pitch size greater than 2^18 = 262144. I’ve searched for threads about using 2d arrays with cudaMallocPitch etc. I made simple program l dst - Destination memory address : dpitch - Pitch of destination memory : src - Source memory address : wOffset - Source starting X offset : hOffset - Source starting Y offset Dec 14, 2019 · what is pitch. h> #include<assert. cudaMemcpy2D is used for copying a flat, strided array, not a 2-dimensional array. i. x+threadIdx. Jul 30, 2015 · I didn’t say cudaMemcpy2D is inappropriately named. I also got very few references to it on this forum. The returned cudaPitchedPtr contains additional fields xsize and ysize, the logical width and height of the allocation, which are equivalent to the width and height extent parameters provided by the programmer during allocation. Jul 29, 2009 · Update: With reference to above post, the program gives bizarre results when matrix size is increased say 10 * 9 etc . gpuErrchk(cudaMemcpy2D(devPtr, pitch, hostPtr, Ncols*sizeof(float), Ncols*sizeof(float), Nrows, cudaMemcpyHostToDevice)); Nov 7, 2023 · 文章浏览阅读6. If the naming leads you to believe that cudaMemcpy2D is designed to handle a doubly-subscripted or a double-pointer referenceable May 19, 2023 · Please read the documentation for cudaMallocPitch. Why does the program give bizarre results when data on host is in 2D Mar 6, 2009 · Nothing stands out as wrong, although the pitch of 832 is greater than I would have expected. CUDA provides also the cudaMemcpy2D function to copy data from/to host memory space to/from device memory space allocated with cudaMallocPitch. The non-overlapping requirement is non-negotiable and it will fail if you try it. I know, someone might suggest of arranging bodies in multiple shorter rows, as. The simple fact is that many folks conflate a 2D array with a storage format that is doubly-subscripted, and also, in C, with something that is referenced via a double pointer. This is not supported and is the source of the segfault. 那时候,我正好完成了立体匹配算法的cuda实现,掌握了一些实实在在的cuda编程知识,我从我的博士论文里把cuda部分整理出来写了两篇很基础的科普文。 Nov 28, 2008 · hardware there is a limitation: max memory pitch= 262144 bytes!! This would allow for maximum 10k bodies in a row, and I must work with larger number of bodies. ) Copies a matrix (height rows of width bytes each) from the memory area pointed to by src to the CUDA array dst starting at the upper left corner (wOffset, hOffset) where kind is one of cudaMemcpyHostToHost, cudaMemcpyHostToDevice, cudaMemcpyDeviceToHost, or cudaMemcpyDeviceToDevice, and specifies the direction of Jun 1, 2022 · Hi ! I am trying to copy a device buffer into another device buffer. h> #define N 4 global static void MaxAdd(int *A, int *B, int *C, int pitch) { int xid = blockIdx. After allocating the memory I am Mar 5, 2013 · It's not limited in size to 20 x 20. There are 2 dimensions inherent in the Mar 15, 2013 · err = cudaMemcpy2D(matrix1_device, pitch, matrix1_host, 100*sizeof(float), 100*sizeof(float), 100, cudaMemcpyHostToDevice); and similarly for the second call to cudaMemcpy2D . When I tried to do same with image size 640x480, its running perfectly. I’m not sure if I’m using cudaMallocPitch and cudaMemcpy2D correctly but I tried to use cudaMemcpy2D. There are two drawbacks that you have to live with: Some wasted space; A bit more complicated elements access; cudaMallocPitch() Memory allocation of 2D arrays using this function will pad every row if necessary. Due to pitch alignment restrictions in the hardware, this is especially true if the application will be performing 2D memory copies between different regions of device memory (whether linear memory or CUDA arrays). For instance, with basic cudaMemcpy and cudaMalloc the kernel processed in: 1462 usec (good perf) Now with memcpy2D and cudaMallocPitch, the kernel processed in: 56299 usec (really bad perf) Something must be wrong with my code. Thanks. CUDA provides the cudaMallocPitch function to “pad” 2D matrix rows with extra bytes so to achieve the desired alignment.
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