From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 129446 invoked by alias); 10 Feb 2016 15:27:45 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 129370 invoked by uid 89); 10 Feb 2016 15:27:45 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 10 Feb 2016 15:27:44 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id DD69419F97D; Wed, 10 Feb 2016 15:27:42 +0000 (UTC) Received: from localhost.localdomain (vpn1-7-13.ams2.redhat.com [10.36.7.13]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1AFRfqK002350; Wed, 10 Feb 2016 10:27:41 -0500 Subject: Re: Un-parallelized OpenACC kernels constructs with nvptx offloading: "avoid offloading" To: Thomas Schwinge , Jakub Jelinek References: <87r3hac1w9.fsf@hertz.schwinge.homeip.net> <569D2059.4010105@mentor.com> <87d1subnu5.fsf@hertz.schwinge.homeip.net> <87a8nyawph.fsf@hertz.schwinge.homeip.net> <20160122083625.GL3017@tucnak.redhat.com> <56A22C2E.6000408@redhat.com> <20160122132538.GT3017@tucnak.redhat.com> <56A22F37.5010505@redhat.com> <87zivg8rcy.fsf@hertz.schwinge.homeip.net> <87h9hg9450.fsf@hertz.schwinge.homeip.net> <56BB3A5E.6000506@redhat.com> <87d1s48w97.fsf@hertz.schwinge.homeip.net> Cc: gcc-patches@gcc.gnu.org, Tom de Vries From: Bernd Schmidt Message-ID: <56BB56EC.90707@redhat.com> Date: Wed, 10 Feb 2016 15:27:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <87d1s48w97.fsf@hertz.schwinge.homeip.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-02/txt/msg00696.txt.bz2 On 02/10/2016 03:39 PM, Thomas Schwinge wrote: > Yes, we need a hammer that big: we have to ensure consistency between > data regions on the device and code offloading to the device, as > otherwise we'll very easily run into inconsistencies, because of the > non-shared memory. In the general case, it's "all or nothing": you > either have to offload all kernels or none of them. That's unfortunately not the impression I got from the earlier discussion, and this seems to imply that one unprofitable kernel would disable all the others - IMO this is not acceptable. There need to be more compiler smarts to figure out whether a kernel is a valid candidate for skipping the offloading. Bernd