[cfe-dev] parallel C++

[Jeff Hammond via cfe-dev]

The path to remote pointers in ISO C++ is long but likely goes through the
heterogeneous working group led by Michael Wong.  I recommend taking a look
at https://github.com/codeplaysoftware/standards-proposals to see what has
been discussed so far.

Jeff

On Tue, Nov 27, 2018 at 8:14 AM Edward Givelberg <ed.givelberg at gmail.com>
wrote:

> Jeff,
> Multi-core CPUs and all the associated software technologies (shared
> memory, threads, etc) are a technological dead end.
> I argue more than that: all software technologies that use processes
> are dead on arrival. This includes the technologies you mention in
> your presentation
>
> https://www.ixpug.org/images/docs/KAUST_Workshop_2018/IXPUG_Invited2_Hammond.pdf
> People got used to processes over decades, so when they talk about
> parallelism they immediately talk about processes, but this is the root of
> the problem. I propose object-level parallelism. An object is more than a
> process. It is a virtual machine.
>
> I propose to introduce remote pointers into C++. I am very surprised
> nobody thought of this before. I'd be curious to know how much work
> people think this would be to do it in LLVM. I know it may be possible to
> introduce something like remote_ptr, but I don't think it is a good idea.
>
> I am also proposing a new way of executing code, which I call causal
> asynchronous execution. I'd like to know if people find it natural to write
> code like this.
>
>
>
>
>
>
>
>
> On Mon, Nov 26, 2018 at 10:26 PM Jeff Hammond <jeff.science at gmail.com>
> wrote:
>
>> I’ll probably have more detailed comments later but the related work you
>> may wish to consider includes:
>> - UPC and Berkeley UPC++
>> - Charm++
>> - HPX from LSU
>> - DASH (http://www.dash-project.org/)
>> - MADNESS (https://arxiv.org/abs/1507.01888)
>>
>> There are quite a few dead parallel C++ dialects from the last millennium
>> but it’s probably not worth your time to find and read about them.
>>
>> I’m very glad that you used MPI as your communication runtime. This will
>> save you lots of pain.
>>
>> Jeff
>>
>> On Mon, Nov 26, 2018 at 2:57 PM Edward Givelberg via cfe-dev <
>> cfe-dev at lists.llvm.org> wrote:
>>
>>>
>>> Chris Lattner suggested that I post to this mailing list.
>>>
>>> I used Clang/LLVM to build a prototype for parallel
>>> interpretation of C++. It's based on the idea that C++
>>> objects can be constructed remotely, and accessed via
>>> remote pointers, without changing the C++ syntax.
>>> I am a mathematician, not an expert on compilers.
>>> I am proposing changes to the C++ standard and to the
>>> compiler architecture, so I'm very interested to hear from
>>> experts.
>>> My paper is
>>> https://arxiv.org/abs/1811.09303
>>> Best regards,
>>> Ed
>>>
>>> -----------------------------------------------------------------
>>> A solution to the problem of parallel programming
>>> E. Givelberg
>>>
>>> The problem of parallel programming is the most important
>>> open problem of computer engineering.
>>> We show that object-oriented languages, such as C++,
>>> can be interpreted as parallel programming languages,
>>> and standard sequential programs can be parallelized automatically.
>>> Parallel C++ code is typically more than ten times shorter than
>>> the equivalent C++ code with MPI.
>>> The large reduction in the number of lines of code in parallel C++
>>> is primarily due to the fact that communications instructions,
>>> including packing and unpacking of messages, are automatically
>>> generated in the implementation of object operations.
>>> We believe that implementation and standardization of parallel
>>> object-oriented languages will drastically reduce the cost of
>>> parallel programming.
>>> his work provides the foundation for building a new computer
>>> architecture, the multiprocessor computer, including
>>> an object-oriented operating system and more energy-efficient,
>>> and easily programmable, parallel hardware architecture.
>>> The key software component of this architecture is a compiler
>>> for object-oriented languages.  We describe a novel compiler
>>> architecture with a dedicated back end for the interconnect fabric,
>>> making the network a part of a multiprocessor computer,
>>> rather than a collection of pipes between processor nodes.
>>> Such a compiler exposes the network hardware features
>>> to the application, analyzes its network utilization, optimizes the
>>> application as a whole, and generates the code for the
>>> interconnect fabric and for the processors.
>>> Since the information technology sector's electric power consumption
>>> is very high, and rising rapidly, implementation and widespread
>>> adoption of multiprocessor computer architecture
>>> will significantly reduce the world's energy consumption.
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>
>> --
>> Jeff Hammond
>> jeff.science at gmail.com
>> http://jeffhammond.github.io/
>>
>

-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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