Re: [boost] [compute] review

Subject: Re: [boost] [compute] review
From: Gruenke,Matt (mgruenke_at_[hidden])
Date: 2014-12-28 18:55:06

-----Original Message-----
From: Boost [mailto:boost-bounces_at_[hidden]] On Behalf Of Sebastian Schaetz
Sent: Sunday, December 28, 2014 7:26
To: boost_at_[hidden]
Subject: Re: [boost] [compute] review

> Gruenke,Matt writes:

> C++ AMP is in my opinion a more promising proposal compared to SYCL.
> Developers opt for C++ AMP today. But both SYCL and C++ AMP are
> higher level tools and have the disadvantages of any higher level
> library compared to a lower level library.

How is SYCL a higher-level tool?  Have a look at the provisional spec:

    https://www.khronos.org/registry/sycl

It has equivalents of everything you find in Boost.Compute, *except* for the higher-level functions.  Moreover, they introduce the notion of command groups, and possibly other low level features.

> In addition, they need a custom compiler or compiler extensions.

[Addressed in previous message.  If you have any evidence to support this, please reply to that thread.]

> OpenCL is supposed to be the abstraction layer that does all that, remember?

In fact, that has been the primary factor fueling my interest, over the years.  But there are many systems that still don't support it.  And it's only one solution to this problem.  There will doubtlessly be others, possibly spurred on by the advent of HSA and other technologies yet to arrive on the scene.

> I urge you to not open this can of worms.

I didn't mean to imply that it *needed* to have a backend for XYZ.  I am merely *suggesting* backends such as a threadpool or possibly OpenMP.  My point was about the design - that it should facilitate the addition of backends, in order to address both existing and future systems where OpenCL support is absent or inefficient.

Again, the key point is that the design should accommodate different backends.  Whether a given backend is developed depends on whether there's enough interest for someone to write and maintain it.  And perhaps some backends will exist only as proprietary patches maintained in private repositories of users.  The main contribution of Boost.Compute would then be the framework, interface, and high-level algorithms.

Matt

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