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RE: [PATCH] Inline C99 math functions
- From: "Wilco Dijkstra" <wdijkstr at arm dot com>
- To: "'Carlos O'Donell'" <carlos at redhat dot com>, "Joseph Myers" <joseph at codesourcery dot com>
- Cc: "GNU C Library" <libc-alpha at sourceware dot org>
- Date: Wed, 17 Jun 2015 13:49:28 +0100
- Subject: RE: [PATCH] Inline C99 math functions
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> Carlos O'Donell wrote:
> On 06/15/2015 01:00 PM, Joseph Myers wrote:
> > On Mon, 15 Jun 2015, Wilco Dijkstra wrote:
> >
> >>> Where are the benchmarks for this? Please put them in benchtests so
> >>> actual reproducible figures can be given. That's the standard practice
> >>> for any change being justified on the basis of performance.
> >>
> >> I'll add a benchmark in another patch - it's not trivial as benchtest is not
> >> suitable to accurately time very simple functions, especially when inlined...
> >
> > Well, the benchmark should come first....
>
> Agreed.
>
> If it's not trivial to test the performance... then how did you test it?
>
> How do I test it when reviewing the patch?
Besides checking it was correctly inlining as expected, I ran the usual benchmarks
like SPECFP to check there are no performance regressions due to the math libs.
Adding more inlining is simply a no-brainer, especially when we're talking about 3-4
instruction functions and not just avoiding a call but also a PLT indirection...
This provides more than a factor 15 speedup in my microbenchmarks.
Wilco