[cfe-dev] [Openmp-dev] RFC: Proposing an LLVM subproject for parallelism runtime and support libraries
C Bergström via cfe-dev
cfe-dev at lists.llvm.org
Tue Mar 15 08:09:52 PDT 2016
On Tue, Mar 15, 2016 at 6:44 PM, Chandler Carruth <chandlerc at google.com> wrote:
> On Mon, Mar 14, 2016 at 6:51 PM Jason Henline via cfe-dev
> <cfe-dev at lists.llvm.org> wrote:
>> I think it would be great if StreamExecutor could use liboffload to
>> perform its offloading under the hood. Right now offloading is handled in
>> StreamExecutor using platform plugins, so I think it could be very natural
>> for us to write a plugin which basically forwards to liboffload.
> I think that having a liboffload plugin would be nice, but I don't think we
> should really base everything on top of this for a few reasons:
> 1) I think we already have a nice plugin interface specifically designed to
> support out-of-tree platforms with StreamExecutor, and it wouldn't make a
> lot of sense to force them to re-implement there stuff.
> 2) Some platforms may not want or be able to use the liboffload style
> It seems like if the OpenMP folks want to add a liboffload plugin to
> StreamExecutor, that would be an awesome additional platform, but I don't
> see why we need to force the coupling here.
I see the distinction of being "agnostic" and welcoming different
plugins, but at the same time I asked how Google was engaging hw
stakeholders. The feedback from Intel if I heard them correctly - they
would warmly welcome some liboffload integration. (Which would enable
PHI support if I'm not mistaken?)
While I don't think anyone will try to block the integration of this
on whether it does or doesn't have support for liboffload - I think
you may win more friends if it does.
IMHO, until this gets market traction I don't think it's ready for
inclusion. There's lots of really great ideas, but there should be
some threshold of _____________ (importance?) before it's included. (I
apologize I can't word this previous sentence perfectly) /* I really
wish there was some way to have it be an "incubator" before formal
Down the road it raises other questions like is it something google
would want enabled and packaged by default?
Also on a technical level I'd like to see some roadmap which Google
plans and if/how they will get feedback from the industry/users/etc.
This ties into previous comments - is it a "standard" or how will you
develop it - openly, semi-open or entirely behind closed doors.
Without a good testsuite and examples - it doesn't feel like there's a
lot of commitment to it. (I apologize as I may have missed if such a
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