From patchwork Thu Aug 1 12:20:40 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhen Lei X-Patchwork-Id: 11070619 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4936913AC for ; Thu, 1 Aug 2019 12:21:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3924426B39 for ; Thu, 1 Aug 2019 12:21:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2D3C228560; Thu, 1 Aug 2019 12:21:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5FB5C26B39 for ; Thu, 1 Aug 2019 12:21:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=hZVxHFstyaxo43ubsBufGsuTZkfc0NGvCR4lKWJ2hP8=; b=A5hBjwWzw2JqPr cbmxvBlq/UKIlszgbAIMTGaaemC6LF9P3Zf0rZPNzPNyYrBmvi1eZnSRxlqw9HcFDTEFivYyStpyo brVmDS66f7GrPneu8fiOuDiKC2N0ks7Bs8Xj9dhpWnKd8JV0xXOW3oBlzYdEckwUldNVPzEyybJX1 YrH4rX/KmZ1pr1a6yj2ySQQWmfupL5UWaO+DDH7zSeNGDNE4q8Ed9K1dH+CGza6HGvijVS/gbGzYb tnG6tO3RLWlCVeGxrbIyKA2TpoX4RO6zMfin4nD5na9oZiodFEjgTQM5ugBwKVU9fb9db5Kr4mFeW M20IAGqjd5A2631RoxYw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1htA5f-0000ZJ-SU; Thu, 01 Aug 2019 12:21:51 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1htA5c-0000Y9-Ig for linux-arm-kernel@lists.infradead.org; Thu, 01 Aug 2019 12:21:50 +0000 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 5C0348E4323954FF7DE6; Thu, 1 Aug 2019 20:21:41 +0800 (CST) Received: from HGHY4L002753561.china.huawei.com (10.133.215.186) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.439.0; Thu, 1 Aug 2019 20:21:31 +0800 From: Zhen Lei To: Jean-Philippe Brucker , John Garry , Robin Murphy , Will Deacon , Joerg Roedel , linux-arm-kernel , iommu , linux-kernel Subject: [PATCH] iommu/arm-smmu-v3: add nr_ats_masters to avoid unnecessary operations Date: Thu, 1 Aug 2019 20:20:40 +0800 Message-ID: <20190801122040.26024-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.21.0.windows.1 MIME-Version: 1.0 X-Originating-IP: [10.133.215.186] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190801_052148_789494_3D8204E3 X-CRM114-Status: GOOD ( 13.52 ) 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: Zhen Lei Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP When (smmu_domain->smmu->features & ARM_SMMU_FEAT_ATS) is true, even if a smmu domain does not contain any ats master, the operations of arm_smmu_atc_inv_to_cmd() and lock protection in arm_smmu_atc_inv_domain() are always executed. This will impact performance, especially in multi-core and stress scenarios. For my FIO test scenario, about 8% performance reduced. In fact, we can use a atomic member to record how many ats masters the smmu contains. And check that without traverse the list and check all masters one by one in the lock protection. Fixes: 9ce27afc0830 ("iommu/arm-smmu-v3: Add support for PCI ATS") Signed-off-by: Zhen Lei --- drivers/iommu/arm-smmu-v3.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index a9a9fabd396804a..1b370d9aca95f94 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -631,6 +631,7 @@ struct arm_smmu_domain { struct io_pgtable_ops *pgtbl_ops; bool non_strict; + atomic_t nr_ats_masters; enum arm_smmu_domain_stage stage; union { @@ -1531,7 +1532,7 @@ static int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, struct arm_smmu_cmdq_ent cmd; struct arm_smmu_master *master; - if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_ATS)) + if (!atomic_read(&smmu_domain->nr_ats_masters)) return 0; arm_smmu_atc_inv_to_cmd(ssid, iova, size, &cmd); @@ -1869,6 +1870,7 @@ static int arm_smmu_enable_ats(struct arm_smmu_master *master) size_t stu; struct pci_dev *pdev; struct arm_smmu_device *smmu = master->smmu; + struct arm_smmu_domain *smmu_domain = master->domain; struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev); if (!(smmu->features & ARM_SMMU_FEAT_ATS) || !dev_is_pci(master->dev) || @@ -1887,12 +1889,15 @@ static int arm_smmu_enable_ats(struct arm_smmu_master *master) return ret; master->ats_enabled = true; + atomic_inc(&smmu_domain->nr_ats_masters); + return 0; } static void arm_smmu_disable_ats(struct arm_smmu_master *master) { struct arm_smmu_cmdq_ent cmd; + struct arm_smmu_domain *smmu_domain = master->domain; if (!master->ats_enabled || !dev_is_pci(master->dev)) return; @@ -1901,6 +1906,7 @@ static void arm_smmu_disable_ats(struct arm_smmu_master *master) arm_smmu_atc_inv_master(master, &cmd); pci_disable_ats(to_pci_dev(master->dev)); master->ats_enabled = false; + atomic_dec(&smmu_domain->nr_ats_masters); } static void arm_smmu_detach_dev(struct arm_smmu_master *master) @@ -1915,10 +1921,10 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master) list_del(&master->domain_head); spin_unlock_irqrestore(&smmu_domain->devices_lock, flags); - master->domain = NULL; arm_smmu_install_ste_for_dev(master); arm_smmu_disable_ats(master); + master->domain = NULL; } static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)