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Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Bernd Schmidt <bschmidt at redhat dot com>
- Cc: Thomas Schwinge <thomas at codesourcery dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 22 Jan 2016 14:25:38 +0100
- Subject: Re: [gomp4] Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading"
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- References: <87r3hac1w9 dot fsf at hertz dot schwinge dot homeip dot net> <569D2059 dot 4010105 at mentor dot com> <87d1subnu5 dot fsf at hertz dot schwinge dot homeip dot net> <87a8nyawph dot fsf at hertz dot schwinge dot homeip dot net> <20160122083625 dot GL3017 at tucnak dot redhat dot com> <56A22C2E dot 6000408 at redhat dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Jan 22, 2016 at 02:18:38PM +0100, Bernd Schmidt wrote:
> On 01/22/2016 09:36 AM, Jakub Jelinek wrote:
> >
> >I think it is a bad idea to go against what the user wrote. Warning that
> >some code might not be efficient? Perhaps (if properly guarded with some
> >warning option one can turn off, either on a per-source file or using
> >pragmas even more fine grained). But by default not offloading? That is
> >just wrong.
>
> I'm leaning more towards Thomas' side of the argument. The kernels construct
> is a hint, a "do your best" request to the compiler. If the compiler sees
> that it can't parallelize a loop inside a kernels region, it's probably best
> not to offload it.
What about #pragma oacc parallel? That would never do that?
Jakub