Re: [PATCH 02/16] perf: Add ability to attach registers dump tosample

[Peter Zijlstra]

On Wed, 2012-05-23 at 21:32 +0200, Jiri Olsa wrote:
> +perf_output_sample_regs(struct perf_output_handle *handle,
> +                       struct pt_regs *regs, u64 mask)
> +{
> +       int i = 0;
> +
> +       do {
> +               u64 val;
> +
> +               if (mask & 1) {
> +                       val = perf_reg_value(regs, i);
> +                       perf_output_put(handle, val);
> +               }
> +
> +               mask >>= 1;
> +               i++;
> +       } while (mask);
> +} 

we have bitmap functions available that can do this far faster on a
number of architectures (like x86) that have bit scanning instructions.

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