From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from esa1.mentor.iphmx.com (esa1.mentor.iphmx.com [68.232.129.153]) by sourceware.org (Postfix) with ESMTPS id 7CBCE3953D39 for ; Tue, 10 Aug 2021 10:10:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7CBCE3953D39 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=codesourcery.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=mentor.com IronPort-SDR: vK/BXxeC2xfj9wlxODqnV/ZAVqV06y2dh7HGROYTuj4hZQWtI900sTCj4M8f71Bjej4BiOXSmX fESMWFIpPdwK8dPQ4JbYcYjK0QQ2H9k9ZI4UM7hXgx/bauvXoYblWrSjPCODyxaIZ0ZXm8Hicr 85jNFCELksI1RP7IiA6jN4631OXq2uwrm0RQMOHd5B6k0ZOrb8i8MH1XDBpBortalOZ+wQYwI0 KR7cFvFKsdsytQ/2YByTUVV8qkqFIgZZ01C0TdJzNnRHtnKgAvu2zaZDNB5CxpviuazNylWPYv GR1RA702E9J8Fa5VyGNnHG6E X-IronPort-AV: E=Sophos;i="5.84,310,1620720000"; d="scan'208";a="66966679" Received: from orw-gwy-02-in.mentorg.com ([192.94.38.167]) by esa1.mentor.iphmx.com with ESMTP; 10 Aug 2021 02:10:37 -0800 IronPort-SDR: 2m1Pqp/P8eYoxbvd/uzWTYV0BESGGyWIf6KTEycbxY6E7Pb724ffEOaPkSc1NPvePfhV7ozyXE 9h9VAlTfvdMcmrJxMw/otgaj6MEL7PYDJiwSk4VpxwHP56xqpilz217Dj0KtqMzp2PelXPIYxZ UCYdK3aOWs/Fpy+O2qtB/bXcFz4HZtH1cW9eXUd9AwwzcfUTB++aW6SYtoeMUsssorZ4d1Zoai dQ6PPjx0GJqZ15TC9u/QIvAF510OpCkotojT4jXLgthHaS4Tv/DKtWrxnv7q+vfMwRzrdYf/ta 4bY= Subject: Re: [wwwdocs] gcc-12/changes.html (GCN): >1 workers per gang To: Thomas Schwinge , Gerald Pfeifer , Julian Brown , Andrew Stubbs CC: References: <531ee7a8-0446-8f7b-7504-928426a257c5@codesourcery.com> <87o8a6pube.fsf@euler.schwinge.homeip.net> From: Tobias Burnus Message-ID: <69870f64-b4e2-2f4c-8431-cff45c631cb2@codesourcery.com> Date: Tue, 10 Aug 2021 12:10:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <87o8a6pube.fsf@euler.schwinge.homeip.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: svr-ies-mbx-09.mgc.mentorg.com (139.181.222.9) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, KAM_SHORT, NICE_REPLY_A, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Aug 2021 10:10:49 -0000 Hi all, On 09.08.21 20:53, Gerald Pfeifer wrote: > (Is "CU" a sufficiently established term, or might it make sense > to spell it out?) I don't know =E2=80=93 but we could use "per compute unit (CU)". On 09.08.21 16:27, Thomas Schwinge wrote: > On 2021-08-09T15:55:07+0200, Tobias Burnus wrot= e: >> +++ b/htdocs/gcc-12/changes.html >> +
  • When used as OpenACC device: the limitation of 1 worker per gang,= 2 gangs >> + per CU has been lifted; now up to 16 workers per gang and 40 gang= s per CU >> + are supported. (Except that the hardware limit of 40 workers tota= l may >> + not be exceeded.)
    • > I haven't changed anything related to a "limitation of [...] 2 gangs per > CU has been lifted". Maybe that has already been done earlier, maybe > that still has to be done? I don't know -- Julian? Looking at the current code, it has: if (dims[0] =3D=3D 0) dims[0] =3D get_cu_count (kernel->agent); /* Gangs= . */ Thus at least when nothing else has been specified, it uses #CUs of gangs, running on #CUs CUs, i.e. 1 gang per CU. [OG11 =E2=80=93 but not mainline] What's needed is something like: dims[0] =3D get_cu_count (kernel->agent) * (32 / dims[1]); which I see in OG11 =E2=80=93 oddly, I also see there code like: def->gdims[0] =3D get_cu_count (agent); // * (40 / gcn_threads); In other words: For gangs > #CUs or >1 gang per CU, the following patch is needed: [OG11] https://gcc.gnu.org/g:4dcd1e1f4e6b451aac44f919b8eb3ac49292b308 [email] https://gcc.gnu.org/pipermail/gcc-patches/2020-July/550102.html "not suitable for mainline until the multiple-worker support is merge= d there" @Andrew + @Julian: Do you intent to commit it relatively soon? Regarding the wwwdocs patch, I can hold off until that commit or reword it to only cover the workers part. Thanks Thomas & Gerald for the comments! Tobias ----------------- Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstra=C3=9Fe 201= , 80634 M=C3=BCnchen; Gesellschaft mit beschr=C3=A4nkter Haftung; Gesch=C3= =A4ftsf=C3=BChrer: Thomas Heurung, Frank Th=C3=BCrauf; Sitz der Gesellschaf= t: M=C3=BCnchen; Registergericht M=C3=BCnchen, HRB 106955