Re: [Discuss-gnuradio] QT GUI Segmentation Fault

[West, Nathan]

On Thu, Oct 30, 2014 at 4:07 PM, Michael Rahaim <address@hidden> wrote:
> Just a follow up on this - I was able to resolve the issue with the
> following modifications in the volk_config file:
>
> before:          volk_32fc_32f_multiply_32fc a_avx generic
> changed to:   volk_32fc_32f_multiply_32fc generic generic
>
> before:          volk_32fc_deinterleave_64f_x2 a_avx u_avx
> changed to:   volk_32fc_deinterleave_64f_x2 generic u_avx
>
>
> While I'm happy to have it working again, I don't exactly know what this
> modification actually does. If anyone with knowledge of the volk library can
> give me a quick bit of info about what these modifications are actually
> doing and / or why this would resolve the segfault issue, it would ease my
> mind a bit.
>
> Thanks,
>
> -Mike
>


Hi Mike,

So each VOLK kernel has several internal implementations that are
architecture specific (SSE, AVX, NEON, etc). A call to the VOLK
library looks like volk_32fc_32f_multiply_32fc(output_buffer,
input_buffer0, input_buffer1, number_of_points). Internally VOLK has a
dispatcher that uses the implementation that is "best" for your
machine. The "best" implementation is determined by running
volk_profile which runs all of the implementations available and write
the fastest one to volk_config. At run-time VOLK reads this file to
know which version of each kernel to actually run.

Can you tell me your processor model name and flags? A copy of
/proc/cpuinfo (just one of the processors) would be useful.

Nathan