Why is GPU disabled in default build?

[blueberry]

I'm using DNNL from JVM through a wrapper library. Everything works fine, but, since the wrapper library has to ship pre-built binaries, GPU is not supported, since the binaries follow the default DNNL build, where GPU engine is disabled.

Now, the obvious solution is to "enable everything" in the the DNNL build that ships with the wrapper library. Is that safe?

For example, would the CPU engine continue to work on the system that would execute the end application if there is no OpenCL driver present, assuming that the user does not try to work with a GPU engine, nor try to execute anything on it?

Or, put more simply, is there a reason not to enable GPU engine by default (in DNNL, but more specifically in wrapper libraries)?

[vpirogov]

Hi @blueberry,

When you build oneDNN with OpenCL runtime the library will be dependent on OpenCL Installable Client Driver (libOpenCL.so):

$ ldd libdnnl.so.1
        linux-vdso.so.1 (0x00007ffe3a532000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fedfe459000)
        libOpenCL.so.1 => /lib/x86_64-linux-gnu/libOpenCL.so.1 (0x00007fedfe24e000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fedfe248000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fedfe067000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fedfdf18000)
        libgomp.so.1 => /lib/x86_64-linux-gnu/libgomp.so.1 (0x00007fedfded6000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fedfdeb9000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fedfdcc7000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fee00732000)

So if ICD is not available in the system the application will fail. It does not matter whether Intel OpenCL Runtime is actually available or not, what matters is the loader. I believe ICD is available on most systems out of the box. Other than that CPU engine should work as expected.

[blueberry]

Thanks!