From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEC62C433B4 for ; Wed, 28 Apr 2021 10:05:59 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5A15261155 for ; Wed, 28 Apr 2021 10:05:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5A15261155 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A46836EB08; Wed, 28 Apr 2021 10:05:53 +0000 (UTC) Received: from mail-wr1-x434.google.com (mail-wr1-x434.google.com [IPv6:2a00:1450:4864:20::434]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9CE146EB07 for ; Wed, 28 Apr 2021 10:05:51 +0000 (UTC) Received: by mail-wr1-x434.google.com with SMTP id z6so1110653wrm.4 for ; Wed, 28 Apr 2021 03:05:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=2ak0GS7Zz2HK1tQiSaR6y4KZgfRU/bog+4Klh4afe48=; b=ih+dCK6ZRqNdbWQPJdHUu2OoeHDTHub27aa3fjKVbgXXPbZwofktN32SIM3avxTfhh EXFEeQU5ZLMZ2VDsx18shduQhWTFpp3cOlyt2cIZ4X66zDC6tPfIqSyRcKgj3mBktkzd Zfadz5s08mk6Q/wY6bRLXpH+SJS4YurJs1EZY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=2ak0GS7Zz2HK1tQiSaR6y4KZgfRU/bog+4Klh4afe48=; b=lxu38J/4xNNw0QwmhVnoqYQkuuyGNq7T+bmp405co3EhfhC+oP+aFheea3IDWSzcme rz/fbUJ74Bmn09dGPKgOejR/4PD5dQmdoOf1sco1SGJCLjlnw1p7upyMA3+ufmJSikz0 8fRo5HWo2CTd/663l2Ac60AhmW3W8AdoScLbdFPFx/D2tfzyczZ0ypZZ4wOkL4WA/1p9 fwuyiBDzLtOPx1DZV3b9OmWSfs4dmGSaq1E6YTgu7HIlkP/bbs7cA+GVTadKUPHL7LOC eH16tkBeounogxGTcSeGrTHnalY9i+SUZiYQlmJK2pz5zeUQYmdMoTliqNZC/KkCkWaJ csow== X-Gm-Message-State: AOAM531YqqNGSl6kMPXgGKA5HpVxkCrJwmqEld1ByGKYEMnad8w3bDBj NYNZNdred4nr6Pk3ONGh6YBabQ== X-Google-Smtp-Source: ABdhPJwCbTin9v4kqTMiQcB75Owjm4KgJbiuVrCEjDCBeARSl9+LsgCjWMcNBqkPX0ztTde1kTDQqg== X-Received: by 2002:adf:d0c8:: with SMTP id z8mr35496956wrh.68.1619604350391; Wed, 28 Apr 2021 03:05:50 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id j13sm9761262wrd.81.2021.04.28.03.05.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 03:05:49 -0700 (PDT) Date: Wed, 28 Apr 2021 12:05:47 +0200 From: Daniel Vetter To: Alex Deucher Subject: Re: [Mesa-dev] [RFC] Linux Graphics Next: Explicit fences everywhere and no BO fences - initial proposal Message-ID: References: <735e0d2e-f2c9-c546-ea6c-b5bbb0fe03a6@gmail.com> <23ea06c825279c7a9f7678b335c7f89437d387ed.camel@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.10.32scarlett+ X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ML Mesa-dev , dri-devel , Christian =?iso-8859-1?Q?K=F6nig?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, Apr 27, 2021 at 02:01:20PM -0400, Alex Deucher wrote: > On Tue, Apr 27, 2021 at 1:35 PM Simon Ser wrote: > > > > On Tuesday, April 27th, 2021 at 7:31 PM, Lucas Stach wrote: > > > > > > Ok. So that would only make the following use cases broken for now: > > > > > > > > - amd render -> external gpu > > > > - amd video encode -> network device > > > > > > FWIW, "only" breaking amd render -> external gpu will make us pretty > > > unhappy > > > > I concur. I have quite a few users with a multi-GPU setup involving > > AMD hardware. > > > > Note, if this brokenness can't be avoided, I'd prefer a to get a clear > > error, and not bad results on screen because nothing is synchronized > > anymore. > > It's an upcoming requirement for windows[1], so you are likely to > start seeing this across all GPU vendors that support windows. I > think the timing depends on how quickly the legacy hardware support > sticks around for each vendor. Yeah but hw scheduling doesn't mean the hw has to be constructed to not support isolating the ringbuffer at all. E.g. even if the hw loses the bit to put the ringbuffer outside of the userspace gpu vm, if you have pagetables I'm seriously hoping you have r/o pte flags. Otherwise the entire "share address space with cpu side, seamlessly" thing is out of the window. And with that r/o bit on the ringbuffer you can once more force submit through kernel space, and all the legacy dma_fence based stuff keeps working. And we don't have to invent some horrendous userspace fence based implicit sync mechanism in the kernel, but can instead do this transition properly with drm_syncobj timeline explicit sync and protocol reving. At least I think you'd have to work extra hard to create a gpu which cannot possibly be intercepted by the kernel, even when it's designed to support userspace direct submit only. Or are your hw engineers more creative here and we're screwed? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel