RFC: What inputs to use for sqrt perf testing

[Siddhesh Poyarekar]

On 4 October 2013 02:55, Steve Ellcey <sellcey@mips.com> wrote:
>
> While making a sqrt performance improvement for MIPS I noticed that there
> was no sqrt performance test in the 'make bench' tests and Joseph suggested
> that we should have one.  It looks like adding it is trivial (see patch),
> but the real question is what input to use.  I just threw in 1.9 and 10000.0
> to test this patch, but I don't think those are necessarily good choices.
>
> Are there any math experts out there could suggest a better selection of
> inputs for sqrt to use in the performance tests?
>
> Here is my strawman patch, I don't expect this to get checked in as it
> is, I am just including it for reference purposes.

The method I'm using for this is to add probes at various branch
points within the function and use a systemtap script to print out the
input whenever the probe point is hit.  This is a bit slow (in terms
of effort), but would ensure good coverage.  Also, as a starting
point, I wouldn't mind having your strawman patch in and then more
inputs added to it when you have them ready.

Siddhesh
-- 
http://siddhesh.in