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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 39E6BC4338F for ; Tue, 17 Aug 2021 17:34:48 +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 ED7A360560 for ; Tue, 17 Aug 2021 17:34:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org ED7A360560 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 502556E213; Tue, 17 Aug 2021 17:34:47 +0000 (UTC) Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by gabe.freedesktop.org (Postfix) with ESMTPS id E8C266E213 for ; Tue, 17 Aug 2021 17:34:45 +0000 (UTC) Received: by mail-wm1-x330.google.com with SMTP id f9-20020a05600c1549b029025b0f5d8c6cso2476470wmg.4 for ; Tue, 17 Aug 2021 10:34:45 -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=dzfhaMDtK0Ye+zUuvV7wuHrtwGmS9fpv0a8hAoUkTu4=; b=Qjpe4xum3r88LA9oxgZ2IIdzP943P/55b7u/TkNNssGn+RUOXaR5mgUpcuNmVvQA5E xNxqRbwIsAmAnUDJkpUONHTKU/GxwXPLBpVjPxunxiJU0OTW15BbG2YyTH1KcCj6NT13 cHmhUa3SHL1bm4gvx2hnNpYxHgOYw9voLYmqg= 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=dzfhaMDtK0Ye+zUuvV7wuHrtwGmS9fpv0a8hAoUkTu4=; b=OZK/REJT9YYOtvC69KIlo13U7Pc4KPbLiJDtjVSw0eNjSh0K2tmScLtYVXGxh6GgXE 6xHrw7us18kWSGwDP38MrkjE2zk3quHIe0IOmupdCOrd0P7CEqp/l39P745QEkq/fLeu PMcRFITm+JzvSPP24mU6fcUovzEBuKiWWsIc/7rRAuWC4dXuz2fVIQZQ/Paky4wk/YwQ TkE/R2/zKccwKAwkpYuUU73dc3uqx9hOQ94KUTuMUndKnrkbGIJwM57fkJua9E0+PjFR 57HyB7SRV5WzIN8U9yfkPwj5qDdZxV+MipmchLhQkw+nOKFAYlekS8g/RAVRzANxSCsT Qg1w== X-Gm-Message-State: AOAM532jnClDyXVbcuY0hHMC8STXi6czTgyzKoaDqmKA8fa7eu3ocKcq ZwxbZOi8feLP5cFzwzoPQ2wpew== X-Google-Smtp-Source: ABdhPJw1AZMT9msnFo7pm/FX64I+UJPudPSJt5NGlr+gmOprS2seFoRfOq6yMkJvB+FBuN2El01XHA== X-Received: by 2002:a1c:4c:: with SMTP id 73mr4520558wma.139.1629221684422; Tue, 17 Aug 2021 10:34:44 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id w14sm3070462wrt.23.2021.08.17.10.34.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Aug 2021 10:34:43 -0700 (PDT) Date: Tue, 17 Aug 2021 19:34:42 +0200 From: Daniel Vetter To: Michal Wajdeczko Cc: Daniel Vetter , Matthew Brost , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch Message-ID: References: <20210816135139.10060-1-matthew.brost@intel.com> <20210816135139.10060-23-matthew.brost@intel.com> <20210817163647.GA30445@jons-linux-dev-box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.10.0-7-amd64 Subject: Re: [Intel-gfx] [PATCH 22/22] drm/i915/guc: Add GuC kernel doc X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, Aug 17, 2021 at 07:27:18PM +0200, Michal Wajdeczko wrote: > > > On 17.08.2021 19:20, Daniel Vetter wrote: > > On Tue, Aug 17, 2021 at 09:36:49AM -0700, Matthew Brost wrote: > >> On Tue, Aug 17, 2021 at 01:11:41PM +0200, Daniel Vetter wrote: > >>> On Mon, Aug 16, 2021 at 06:51:39AM -0700, Matthew Brost wrote: > >>>> Add GuC kernel doc for all structures added thus far for GuC submission > >>>> and update the main GuC submission section with the new interface > >>>> details. > >>>> > >>>> Signed-off-by: Matthew Brost > >>> > >>> There's quite a bit more, e.g. intel_guc_ct, which has it's own world of > >>> locking design that also doesn't feel too consistent. > >>> > >> > >> That is a different layer than GuC submission so I don't we should > >> mention anything about that layer here. Didn't really write that layer > >> and it super painful to touch that code so I'm going to stay out of any > >> rework you think we need to do there. > > > > Well there's three locks > > It's likely me. > > There is one lock for the recv CTB, one for the send CTB, one for the > list of read messages ready to post process - do you want to use single > lock for both CTBs or single lock for all cases in CT ? > > Michal > > disclaimer: outstanding_g2h are not part of the CTB layer Why? Like apparently there's not enough provided by that right now, so Matt is now papering over that gap with more book-keeping in the next layer. If the layer is not doing a good job it's either the wrong layer, or shouldn't be a layer. And yeah the locking looks like serious amounts of overkill, was it benchmarked that we need the 3 separate locks for this? While reading ctb code I also noticed that a bunch of stuff is checked before we grab the relevant spinlocks, and it's not - wrapped in a WARN_ON or GEM_BUG_ON or similar to just check everything works as expected - there's no other locks So either racy, buggy or playing some extremely clever tricks. None of which is very good. -Daniel > > > > there plus it leaks out (you have your > > outstanding_submission_g2h atomic_t which is very closed tied to well, > > outstanding guc transmissions), so I guess I need someone else for that? > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch