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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 7E67AC433E2 for ; Thu, 17 Sep 2020 12:05:40 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 09DD020684 for ; Thu, 17 Sep 2020 12:05:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Dxx7nrMd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 09DD020684 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=bGBYcIfULBT5E4TQsSktqEQcILygzpbU17veQ8f9ZEk=; b=Dxx7nrMdqQiCZIZarlqP2FJLn Nf3eUFBQIqe+OUhObMGKg0ex+F6rDYB9RxBiJ1wazL0ocC7iaavlgbnjwUBWDURCW/ztHTM29Hn5c qxbkytlb1DpVIdhGSYO4+Ume5cWwULYnIGRO8hRi0iqNN/ni+zUF7DwsniEsqkVvYTsRXmyur82Xx P0i45n3FjdJlQZ9rYplvkmcaCi5/3oa6sKCmMiO4PL0zHdsVPRyB8XHSV8OQXnjKxFl1ksW1YGTw2 k/cX8lE7lj6ZBnG4NeMbpNYKJum5yIPP/b7O9EWqzIM7jHkUka0LUlU4jLK0BJ1Ubl1EQVpgRJ6cU el8e0svFQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIsdy-0008C0-1v; Thu, 17 Sep 2020 12:04:06 +0000 Received: from bhuna.collabora.co.uk ([2a00:1098:0:82:1000:25:2eeb:e3e3]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIsdu-0008B0-GZ; Thu, 17 Sep 2020 12:04:03 +0000 Received: from kevin (unknown [IPv6:2607:fea8:55f:a950::68f4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: alyssa) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id C9FB029AEF5; Thu, 17 Sep 2020 13:03:47 +0100 (BST) Date: Thu, 17 Sep 2020 08:03:37 -0400 From: Alyssa Rosenzweig To: Steven Price Subject: Re: [PATCH 0/3] drm: panfrost: Coherency support Message-ID: <20200917120337.GA1684@kevin> References: <20200916170409.GA2543@kevin> MIME-Version: 1.0 In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200917_080402_640781_CE02719B X-CRM114-Status: GOOD ( 10.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rob Herring , Tomeu Vizoso , Neil Armstrong , Kevin Hilman , Linux IOMMU , dri-devel , Will Deacon , "open list:ARM/Amlogic Meson..." , Robin Murphy , linux-arm-kernel , Jerome Brunet Content-Type: multipart/mixed; boundary="===============0883373776595581825==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0883373776595581825== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="6TrnltStXW4iwmi0" Content-Disposition: inline --6TrnltStXW4iwmi0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > The DDK blob has the ability to mark only certain areas of memory as > coherent for performance reasons. For simple things like kmscube I would > expect that it's basically write-only from the CPU and almost all memory the > GPU touches isn't touched by the CPU. I.e. coherency isn't helping and the > coherency traffic is probably expensive. Whether the complexity is worth it > for "real" content I don't know - it may just be silly benchmarks that > benefit. Right, Panfrost userspace specifically assumes GPU reads to be expensive and treats GPU memory as write-only *except* for a few special cases (compute-like workloads, glReadPixels, some blits, etc). The vast majority of the GPU memory - everything used in kmscube - will be write-only to the CPU and fed directly into the display zero-copy (or read by the GPU later as a dmabuf). --6TrnltStXW4iwmi0 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEQ17gm7CvANAdqvY4/v5QWgr1WA0FAl9jUJAACgkQ/v5QWgr1 WA2dWg/+OmkKrIz3I3zxUDFk1aW47mEA/JzLjdkrFq+J1K67FPajUIaqzgLjYq1b wB3a51QSJoN70Aw9O9jrV/GkEbpSf8QWObN4NtZqYcD58fECprh5oXmEfgD0u5gZ 6Gkoijp15utLoOirt2LkEJpYAxrOjfA9n5+WQLn8qQY1QPwO2AjtNxXWlWNhYqvh CQwDQGoO9FiWNSRPZpx1yHEYP/aDMTW8MqwQ8JsQu2G42TS6ErQUC9OMMZjJ/TYS GLKA4ybkdSnlNwQH0h+7g6LX0Y3WGUUn1xxbd4P7OPFZapV+87+cQS8sottqH7tS Rrja9cH4d7/DjKmn1xjT5ftnagxGkzoJ9eYf13DTedymUAQxMGV5TdZhCeUT0HFz 5es9SnkTjOFAQyKZbjiM5t5Sia0eUHLIKUwX6FFKnWxMTtLF4z8XGhizHQrZ8M5I tQW8f7BzInUEGN5H3FV6spp+P5tL7AkdTEGJ4p87EnoyJfTq2mxWAfTxxN9R01FQ 3yDMyx9bUXif0CNnJjAyTN0WJt17twGKuqAnGu5+oLtK6BXuC5wv9yPyQZ5Zvwgv HnXnb+s10WYXgdOHRNebUvFnDYsIZTp8/qFXiAdKaHT/r7aL/UKm2XQqwz48O40W doi8CBItWk7+SxVkj3w5nxnyl9vhu0Md9HkBvGZEH3wfnPGu4/w= =k8jL -----END PGP SIGNATURE----- --6TrnltStXW4iwmi0-- --===============0883373776595581825== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============0883373776595581825==--