Allocate memory object on device only ?

From what I know about JOCL, the context.create****Buffer function always allocate 2 version of buffers, one in host, and one in device. However, in some cases, I need to create the device one only; to use it as a temporary buffer, for instance. Is it possible to do so ?

  Hello fqhuy,

a CLBuffer usually holds a direct allocated buffer (can be any type of
java.nio.Buffer). This buffer is used when you enqueue synchronous or
asynchronous write/read commands in a CLCommandQueue.

example (junit test):
         CLBuffer<ByteBuffer> clBufferA = context.createByteBuffer(elements*SIZEOF_INT, mem.READ_ONLY);
         CLBuffer<ByteBuffer> clBufferB = context.createByteBuffer(elements*SIZEOF_INT, mem.READ_ONLY);

         // asynchronous write of data to GPU device, blocking read later to get the computed results back.
         queue.putWriteBuffer(clBufferA, false)                                 // write A
              .putCopyBuffer(clBufferA, clBufferB, clBufferA.buffer.capacity()) // copy A -> B
              .putReadBuffer(clBufferB, true)                                   // read B
              .finish();


If you don't need this nio buffer but only the on-device counterpart use
one of the create methods with the question mark in it:

CLBuffer<?> createBuffer(int size, CLMemory.Mem... flags)
http://jogamp.org/deployment/webstart-next/javadoc/jocl/javadoc/com/jogamp/opencl/CLContext.html#createBuffer%28int,%20com.jogamp.opencl.CLMemory.Mem...%29

this will give you a CLBuffer<?> without a NIO buffer (that was
basically your question).

you can change this later at runtime if you want:
just use buffer.cloneWith(niobuffer) to get a new instance of a CLBuffer
pointing to the same device buffer but using a different NIO buffer.

(everything above applies for CLImages, CLGLBuffers and CLGLTextures also)

hope that helps,
michael


On 02/10/2011 11:16 AM, fqhuy [via jogamp] wrote:
>
> > From what I know about JOCL, the context.create****Buffer function always
> allocate 2 version of buffers, one in host, and one in device. However, in
> some cases, I need to create the device one only; to use it as a temporary
> buffer, for instance. Is it possible to do so ?
>
>
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