Re: Is offloading to GPU a worthwhile feature?

From: Jakub Narebski <jnareb@gmail.com>
Date: Apr 8, 2018, 13:59 UTC
Message-ID: <86k1thdck7.fsf@gmail.com>
In-Reply-To: <efc4af6b-53c9-bd02-65f6-9de517f6868e@linuxfoundation.org>

Hello,

Konstantin Ryabitsev <konstantin@linuxfoundation.org> writes:

Show 12 quoted lines

> This is an entirely idle pondering kind of question, but I wanted to
> ask. I recently discovered that some edge providers are starting to
> offer systems with GPU cards in them -- primarily for clients that need
> to provide streaming video content, I guess. As someone who needs to run
> a distributed network of edge nodes for a fairly popular git server, I
> wondered if git could at all benefit from utilizing a GPU card for
> something like delta calculations or compression offload, or if benefits
> would be negligible.
>
> I realize this would be silly amounts of work. But, if it's worth it,
> perhaps we can benefit from all the GPU computation libs written for
> cryptocoin mining and use them for something good. :)

The problem is that you need to transfer the data from the main memory (host memory) geared towards low-latency thanks to cache hierarchy, to the GPU memory (device memory) geared towards bandwidth and parallel access, and back again. So to make sense the time for copying data plus the time to perform calculations on GPU (and not all kinds of computations can be speed up on GPU -- you need fine-grained massively data-parallel task) must be less than time to perform calculations on CPU (with multi-threading).

Also you would need to keep non-GPU and GPGPU code in sync. Some parts of code do not change much; and there also solutions to generate dual code from one source.

Still, it might be good idea,

-- 
Jakub Narębski