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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 B4C03C433E2 for ; Wed, 16 Sep 2020 17:47:59 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 455C0206B6 for ; Wed, 16 Sep 2020 17:47:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="B5ESeMEU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 455C0206B6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id DF4CE2E0EA; Wed, 16 Sep 2020 17:47:58 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IkwfLnEoQgxY; Wed, 16 Sep 2020 17:47:51 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id CA5FA2E112; Wed, 16 Sep 2020 17:46:45 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id AE938C0864; Wed, 16 Sep 2020 17:46:45 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 35C76C0051 for ; Wed, 16 Sep 2020 17:46:44 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 328518742E for ; Wed, 16 Sep 2020 17:46:44 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id OCfBowUVp2yq for ; Wed, 16 Sep 2020 17:46:43 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by whitealder.osuosl.org (Postfix) with ESMTPS id A85BC8741A for ; Wed, 16 Sep 2020 17:46:43 +0000 (UTC) Received: from mail-oi1-f169.google.com (mail-oi1-f169.google.com [209.85.167.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 19052206DC for ; Wed, 16 Sep 2020 17:46:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600278403; bh=T7fAAdGMEwmTUz3pfaivZhFKXEL+DDksEtd73K/d1go=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=B5ESeMEUtj1Na7fmLooTO8GkHarnHss8zBYCfN/dmFbqoxSgiuinIyUxGXgDBiHRD wVyiSJIvR2essfm0M43MtG9+p1eZkTr/kBrVnLRsjPY6AVwDHkkeciV16Nwyt618Qi AQzbMGHh21c31NP/94SPiEy7qaTP3ohI6MHi7vzI= Received: by mail-oi1-f169.google.com with SMTP id x14so9047995oic.9 for ; Wed, 16 Sep 2020 10:46:43 -0700 (PDT) X-Gm-Message-State: AOAM531aO+vo1bF9qv7Ocujz/DW/X5ep6oTXrrz/rVbTMOb/6bE3Q0BW Fp1qoM9sSnTKSdfELB7J/2cZU5RaunIhAUNDnw== X-Google-Smtp-Source: ABdhPJzrTvS63xEc/YGj1M1VvkjQrHbt5CCRuhwhSuLfTUE5WrBgivzbCA7OeSqMGDgazvs3cRxd8meuptTx472enRI= X-Received: by 2002:aca:1711:: with SMTP id j17mr4051983oii.152.1600278402414; Wed, 16 Sep 2020 10:46:42 -0700 (PDT) MIME-Version: 1.0 References: <20200916170409.GA2543@kevin> In-Reply-To: <20200916170409.GA2543@kevin> From: Rob Herring Date: Wed, 16 Sep 2020 11:46:31 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 0/3] drm: panfrost: Coherency support To: Alyssa Rosenzweig Cc: Tomeu Vizoso , Neil Armstrong , Robin Murphy , dri-devel , Steven Price , Linux IOMMU , Kevin Hilman , "open list:ARM/Amlogic Meson..." , Will Deacon , linux-arm-kernel , Jerome Brunet X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig wrote: > > > So I get a performance regression with the dma-coherent approach, even if it's > > clearly the cleaner. > > That's bizarre -- this should really be the faster of the two. Coherency may not be free. CortexA9 had something like 4x slower memcpy if SMP was enabled as an example. I don't know if there's anything going on like that specifically here. If there's never any CPU accesses mixed in with kmscube, then there would be no benefit to coherency. Rob _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu