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PO
primarykey
Id
17776144
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
CreationDate
2013-07-21T19:40:55.227
FavoriteCount
0
LastActivityDate
2014-03-17T13:56:31.930
LastEditDate
2014-03-17T13:56:31.930
LastEditorUserId
122423
OwnerUserId
2521274
ParentId
17775738
PostTypeId
2
Score
1
ViewCount
0
LastEditorDisplayName
text
Body
My understanding is that CL_MEM_ALLOC_HOST_PTR allocates but doesn't copy. Does the 2nd block of code actually get any data onto the device? Also, clCreateBuffer when used with CL_MEM_USE_HOST_PTR and CL_MEM_COPY_HOST_PTR shouldn't require clEnqueueWrite, as the buffer is created with the memory pointed to by void *host_ptr. Using "pinned" memory in OpenCL should be a process like: <pre><code> int amt = 16*1024*1024; int Array[] = new int[amt]; int Error = 0; //Note, since we are using NULL for the data pointer, we HAVE to use CL_MEM_ALLOC_HOST_PTR //This allocates memory on the devices cl_mem B1 = clCreateBuffer(context, CL_MEM_READ_WRITE | CL_MEM_ALLOC_HOST_PTR, sizeof(int)*amt, NULL, &Error); //Map the Device memory to host memory, aka pinning it int *host_ptr = clEnqueueMapBuffer(queue, B1, CL_TRUE, CL_MAP_READ | CL_MAP_WRITE, 0, sizeof(int)*amt, 0, NULL, NULL, &Error); //Copy from host memory to pinned host memory which copies to the card automatically` memcpy(host_ptr, Array, sizeof(int)*amt); //Call your kernel and everything else and memcpy back the pinned back to host when //you are done </code></pre> Edit: One final thing you can do to speed up the program is to not make the memory read/write blocking by using CL_FALSE instead of CL_TRUE. Just make sure to call clFinish() before data gets copied back to the host so that the command queue is emptied and all commands are processed. Source: <a href="http://www.manning.com/scarpino2/" rel="nofollow">OpenCL In Action</a>
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1. This table or related slice is empty.
PostParentId
1. POCL_MEM_ALLOC_HOST_PTR slower than CL_MEM_USE_HOST_PTR
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PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USAchimnol
UserOwnerUserId
1. USAustin
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1. POCL_MEM_ALLOC_HOST_PTR slower than CL_MEM_USE_HOST_PTR
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1. VO
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2. VO
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1. This table or related slice is empty.

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