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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C4D51C4338F for ; Tue, 10 Aug 2021 18:35:42 +0000 (UTC) Received: from smtp3.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 655BF60E78 for ; Tue, 10 Aug 2021 18:35:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 655BF60E78 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 303B2606A0; Tue, 10 Aug 2021 18:35:42 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id seAX5Ex6gPFF; Tue, 10 Aug 2021 18:35:38 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTPS id 051D3606CB; Tue, 10 Aug 2021 18:35:37 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id D3326C001A; Tue, 10 Aug 2021 18:35:37 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 45807C000E for ; Tue, 10 Aug 2021 18:35:36 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 2E69B4010E for ; Tue, 10 Aug 2021 18:35:36 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp2.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=kernel.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Wt7DzQaG_3Vh for ; Tue, 10 Aug 2021 18:35:35 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp2.osuosl.org (Postfix) with ESMTPS id 8310F400C6 for ; Tue, 10 Aug 2021 18:35:35 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id EF91760E09; Tue, 10 Aug 2021 18:35:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628620535; bh=Ml4HBc7HBEfIexLPEgG1MMBsjGmO0+Y5qNWSj4KGzcU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fkm7yW6lRJB1FQ0aqqeK2ZiM9DHp0v0a+I3UCVNwRGRgumFxs5ZJ41y5ITGoJoYYU ORX371bNKwo7fiLCD7okXzruLK1VEsPaRqGsbxyPPE3/Wgx07zl9jrGOgCowLRaOcB fG69V3faVO8F0/ckJcWahrUUabRtq+9H9c2G8RwfBRK9scyh3EPKy1jbCl/MwhxsXo /iAlwvz8CeBe/H+L8RGbcrQgEfJGaQb2O/RYx5R4QgccUBOef5L4kFjN80dH9VC3py GozgiFgdNYptBv0yYqMZCkdLB++GBeT2xSsu/R9ONnnA/wbiN/1pKvVdqKj8nEtyAo kvYvruxP76MWQ== Date: Tue, 10 Aug 2021 19:35:30 +0100 From: Will Deacon To: Zhen Lei Subject: Re: [PATCH RFC 0/8] iommu/arm-smmu-v3: add support for ECMDQ register mode Message-ID: <20210810183529.GC3296@willie-the-truck> References: <20210626110130.2416-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210626110130.2416-1-thunder.leizhen@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Robin Murphy , iommu , linux-arm-kernel , linux-kernel 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 Sat, Jun 26, 2021 at 07:01:22PM +0800, Zhen Lei wrote: > SMMU v3.3 added a new feature, which is Enhanced Command queue interface > for reducing contention when submitting Commands to the SMMU, in this > patch set, ECMDQ is the abbreviation of Enhanced Command Queue. > > When the hardware supports ECMDQ and each core can exclusively use one ECMDQ, > each core does not need to compete with other cores when using its own ECMDQ. > This means that each core can insert commands in parallel. If each ECMDQ can > execute commands in parallel, the overall performance may be better. However, > our hardware currently does not support multiple ECMDQ execute commands in > parallel. > > In order to reuse existing code, I originally still call arm_smmu_cmdq_issue_cmdlist() > to insert commands. Even so, however, there was a performance improvement of nearly 12% > in strict mode. > > The test environment is the EMU, which simulates the connection of the 200 Gbit/s NIC. > Number of queues: passthrough lazy strict(ECMDQ) strict(CMDQ) > 6 188 180 162 145 --> 11.7% improvement > 8 188 188 184 183 --> 0.55% improvement Sorry, I don't quite follow the numbers here. Why does the number of queues affect the classic "CMDQ" mode? We only have one queue there, right? > In recent days, I implemented a new function without competition with other > cores to replace arm_smmu_cmdq_issue_cmdlist() when a core can have an ECMDQ. > I'm guessing it might get better performance results. Because the EMU is too > slow, it will take a while before the relevant data is available. I'd certainly prefer to wait until we have something we know is representative. However, I can take the first four prep patches now if you respin the second one. At least that's then less for you to carry. I'd also like review from the Arm side on this (and thank you for adopting the architecture unlike others seem to have done judging by the patches floating around). Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu