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linuxopenclgpummapvirtual-memory

Using memory mapped file with OpenCL

I access a file on a disk using memory mapped I/O (mmap call on linux).

Is it possible to pass this virtual memory buffer to OpenCL using CL_MEM_USE_HOST_PTR (for reading only). And could this result in performance gains?

I want to avoid copying an entire file into host memory, and instead let the OpenCL kernel control which parts of the file get loaded/buffered by the operating system.

Solution

  • I think this should work - you shouldn't end up with errors, crashes, or incorrect results; whether or not it brings performance gains probably depends on hardware, driver/CL implementation, and access patterns. I would not be surprised if it didn't make much of a difference in many cases. I could imagine the GPU driver prefaulting and wiring down all the pages in order to map it into the GPU's address space.