I've been doing some reading on zero copy support in the shared memory of CPU and GPU, and I have two questions raised by different forum posts I've seen.
1. Is this supported on Linux? According to http://devgurus.amd.com/thread/158885 it wasn't in March in 2.6.
2. How much of an impact do the read-write permission flags passed to clCreateBuffer and clEnqueueMapBuffer/clEnqueueUnmapMemObject have on performance? The post at http://blogs.amd.com/developer/2011/08/01/cpu-to-gpu-data-transfers-exceed-15gbs-using-apu-zero-copy-path/ only discusses using CL_MEM_READ_ONLY, so does that mean it's generally only considered useful if the memory object in question is read-only on GPU and written on host side?
Thanks in advance for any insight.