Re: [PATCH] v11 Improves __ieee754_exp() performance by greater than 5x on sparc/x86.

[Joseph Myers <joseph@codesourcery.com>]

On Tue, 13 Feb 2018, Patrick McGehearty wrote:

> Any thoughts on general principles on how to decide which patch
> to accept, given both seem much more better than the existing code?

My understanding would be that Szabolcs intends (as per 
<https://sourceware.org/ml/libc-alpha/2018-02/msg00065.html> and 
<https://sourceware.org/ml/libc-alpha/2018-02/msg00061.html>) to eliminate 
rounding mode changes from the present exp, and possibly make other 
speedups there.  Then the final result of such speedups would need 
comparing with a version of your patch that also eliminates rounding mode 
changes (and updates libm-test-ulps expectations for other functions in 
non-default rounding modes as needed to avoid introducing failures).  It 
would be best to have a precise statement of what "both my throughput and 
latency benchmarks" are in 
<https://sourceware.org/ml/libc-alpha/2018-02/msg00061.html>, to make sure 
there is a common basis of comparison so we can see if it's really the 
case that one version is faster on some architectures and another on other 
architectures, or whether different people are measuring different things.

-- 
Joseph S. Myers
joseph@codesourcery.com