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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id CCC13EE01E0 for ; Wed, 13 Sep 2023 17:02:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 12C4110E08B; Wed, 13 Sep 2023 17:02:09 +0000 (UTC) Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [IPv6:2001:67c:2050:0:465::201]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6F16E10E08B for ; Wed, 13 Sep 2023 17:02:07 +0000 (UTC) Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4Rm6F70kM3z9svG; Wed, 13 Sep 2023 19:02:03 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1694624523; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AlKnzk67aSrFYw3ZTw8IBMqRXvLKk29quzRywYlZlNY=; b=jjEV+DgTbcghKhMizj0JhZDNH+k+cAp4WS4mq6Ks5IkjDU0kafDqsuhmoFfLrlR8ClxIi8 Jgu3inFZBEqgiaQRTjbivX43kK8IctDdU3H9VhqKKCXzCkhXxN2NL9lYYUdgwY0lG4fl5R UedplselvF+q3j+CY6ytTXxE+XOO2plO4DX04wNuAajDy8eWvmNhIXRPmCxmJpP5jYBiv2 bq7Pw5fXjRZ8i8iqUSMUaEpAvjcWTVg+yPOgsU1WAzUU8tTwX0V2kSsWx1aUzER1+++DgF VEmgyGzxyRo2BCdFZNInfdWYNAy83SMVaZFfRNlHYjASz5UOFOWyXU+/mdjiIA== Message-ID: <87df2806-43d4-0bd9-e17c-84203ff9625a@mailbox.org> Date: Wed, 13 Sep 2023 19:02:01 +0200 MIME-Version: 1.0 Subject: Re: [PATCH v3] drm/plane: Add documentation about software color conversion. Content-Language: de-CH-frami, en-CA To: Jocelyn Falempe , Thomas Zimmermann References: <20230825140434.182664-1-jfalempe@redhat.com> <3f1bd1ad-cd1f-515d-38bd-63e412dec286@suse.de> <20230908141638.79b31d1e@eldfell> <4e3bd95a-fcda-2e39-46f7-ebbb78ae515d@suse.de> <20230908174113.02b65f9c@eldfell> <6d506fe7-3c23-3b50-2d29-549ccb4dbe87@suse.de> <20230911113827.67ed6c7d@eldfell> <39adc271-b79a-82ab-d125-e25e3282b729@redhat.com> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= In-Reply-To: <39adc271-b79a-82ab-d125-e25e3282b729@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-MBO-RS-ID: ab173ab8cb8b2f4a1e5 X-MBO-RS-META: mqd9mexejh3arpngetmkng3dh5sgt3k5 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: dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 9/13/23 10:14, Jocelyn Falempe wrote: > On 12/09/2023 17:57, Michel Dänzer wrote: >> On 9/11/23 10:38, Pekka Paalanen wrote: >>> On Fri, 8 Sep 2023 17:10:46 +0200 >>> Thomas Zimmermann wrote: >>>> Am 08.09.23 um 16:41 schrieb Pekka Paalanen: >>>>> On Fri, 8 Sep 2023 15:56:51 +0200 >>>>> Thomas Zimmermann wrote: >>>>>> >>>>>> Another point of concern is CPU consumption: Slow I/O buses may stall >>>>>> the display thread, but the CPU could do something else in the meantime. >>>>>> Doing format conversion on the CPU prevents that, hence affecting other >>>>>> parts of the system negatively. Of course, that's more of a gut feeling >>>>>> than hard data. >> >> Jocelyn, have you measured if the XRGB8888 -> RGB888 conversion copy takes longer than a straight RGB888 -> RGB888 copy in the kernel? > > At least on my Matrox system, the conversion is really negligible compared to the copy, due to slow memory bandwidth. I wasn't able to see a difference, using ktime_get_ns(). > > The CPU is an old Intel(R) Core(TM) i3 CPU 540  @ 3.07GHz > in 1280x1024, the RGB888 copy takes 95ms. > and the XRGB8888->RGB888 takes also 95ms. > (and the full XRGB8888 copy takes 125ms) Then any XRGB8888 → RGB888 conversion in user space has to result in worse performance. > But let's admit that this discussion is going nowhere, and that I failed to reach a consensus, so I'm now focusing on other things. I see consensus, with one person disagreeing. -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and Xwayland developer