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Date: Thu, 6 Jun 2019 22:41:27 -0700 (PDT)
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Subject: Re: Toy computational "benchmark" in Ada (new blog post)
From: David Trudgett <dktrudgett@gmail.com>
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Xref: reader01.eternal-september.org comp.lang.ada:56523
Date: 2019-06-06T22:41:27-07:00
List-Id: <comp.lang.ada>

Il giorno venerd=C3=AC 7 giugno 2019 14:50:07 UTC+10, Paul Rubin ha scritto=
:
>=20
> C++ version results: single threaded 45.73 seconds cpu, 47.36 sec elapsed=
.
> Multi-threaded (4 threads): 84.34 sec cpu, 23.11 sec elapsed.

You have not coded the same thing as the Ada code. Do you know any Ada at a=
ll?

>=20
> That's using GCC 6.03 with threading done by std::future's async
> function.  So both versions are a fair amount faster than the Ada
> version, but the threading speedup is nowhere near as good.  I wonder
> what's going on with that.  At each of the 50 calculation runs, I launch
> 4 threads=20

As you should know, the Ada code does not do this.


> for slices of the array, then wait for them to complete and
> sum the results, so there might be a little bit of idle time if the
> threads don't all use the exact same amount of time.

While eye-balling the Ada test runs, it seems that each of the eight tasks =
take virtually identical times. I didn't bother outputting the individual r=
un times, however.

>=20
> I also want to try with transform_map_reduce and maybe the new Intel TBB
> library with GCC 9.  It is possible that transform_map_reduce can use
> Intel SIMD intrinsics but otherwise they can be called directly with
> some hassle.  Also I can run on a machine with AVX512.
>=20
> I guess the next thing after that would be OpenCL or CUDA and a graphics
> card.

Good luck with that! :-)

Cheers,
David