Re: Decimal: Formal review begins

From: Ruben Perez (rubenperez038_at_[hidden])
Date: 2025-01-20 20:52:52

On Mon, 20 Jan 2025, 21:28 Glen Fernandes via Boost, <boost_at_[hidden]>
wrote:

> On Mon, Jan 20, 2025 at 3:11 PM Matt Borland  wrote:
>
> > On Monday, January 20th, 2025 at 12:48 PM, Glen Fernandes  wrote:
> >
> > > I mentioned this to Matt, but I would like to see benchmarks comparing
> > > boost::decimal64_fast to a Decimal64 backed by Intel's DFP library,
> which
> > > is what I know to be in actual use today:
> > >
> >
> https://www.intel.com/content/www/us/en/developer/articles/tool/intel-decimal-floating-point-math-library.html
> > > Not that the benchmarks comparing to GCC's Decimal64 (which is based on
> > the
> > > libbid which ships with libgcc) aren't useful, I personally don't know
> > > anyone using that today.
> > >
> > > Benchmarks should ideally also include Intel's compiler, because at
> least
> > > one of the relevant parties who motivated me to suggest the Decimal64
> > > library (to Vinnie as a potential project) do use the Intel C++
> compiler
> > > (and their Fortran compiler) for areas where they perform better.
> > >
> > > (The non-fast versions don't matter to me. I don't know anyone who
> would
> > > want to use them).
> >
> > Here are some preliminary results:
> >
> > All tests run on an i9-11900k with Ubuntu 24.04 and the Intel(R) oneAPI
> > DPC++/C++ Compiler 2025.0.4 (2025.0.4.20241205). The Intel benchmarks are
> > written in C but should be a faithful port. Bottom line up front is the
> > Intel library is an order of magnitude faster.
> >
>
> Thank you Matt.  This reconciles with what I know about everyone using the
> Intel library (especially the BSL proclamation about it being 10 times
> faster). These numbers should be added to the documentation.
>
> I think there is some work to be done to make Boost.Decimal viable. i.e. We
> don't want to be an order of magnitude slower than what everyone else is
> actually using today.
>

Glen, thanks for pointing this out. In the sight of this new piece of data,
I'm afraid I will be adding a new condition to my ACCEPT vote: the library
should be optimized to be in the same order of magnitude of performance as
the Intel one.

Regards,
Ruben.

> Glen
>
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