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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 49AF5C433DF for ; Thu, 27 Aug 2020 09:33:08 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 27EF5207CD for ; Thu, 27 Aug 2020 09:33:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 27EF5207CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=hisilicon.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id F1B5C87954; Thu, 27 Aug 2020 09:33:07 +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 pQpq2gzFam60; Thu, 27 Aug 2020 09:33:06 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 5F3AC86D81; Thu, 27 Aug 2020 09:33:06 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 57F18C016F; Thu, 27 Aug 2020 09:33:06 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4E345C089E for ; Thu, 27 Aug 2020 09:33:03 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 0ACCF204F2 for ; Thu, 27 Aug 2020 09:33:03 +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 q-FDOQpsulub for ; Thu, 27 Aug 2020 09:33:01 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from huawei.com (szxga05-in.huawei.com [45.249.212.191]) by silver.osuosl.org (Postfix) with ESMTPS id 535732001A for ; Thu, 27 Aug 2020 09:33:01 +0000 (UTC) Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 85B7DE810C22EFFD019F; Thu, 27 Aug 2020 17:32:59 +0800 (CST) Received: from SWX921481.china.huawei.com (10.126.200.71) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.487.0; Thu, 27 Aug 2020 17:32:53 +0800 From: Barry Song To: , Subject: [PATCH v5 3/3] iommu/arm-smmu-v3: permit users to disable msi polling Date: Thu, 27 Aug 2020 21:29:57 +1200 Message-ID: <20200827092957.22500-4-song.bao.hua@hisilicon.com> X-Mailer: git-send-email 2.21.0.windows.1 In-Reply-To: <20200827092957.22500-1-song.bao.hua@hisilicon.com> References: <20200827092957.22500-1-song.bao.hua@hisilicon.com> MIME-Version: 1.0 X-Originating-IP: [10.126.200.71] X-CFilter-Loop: Reflected Cc: robin.murphy@arm.com, will@kernel.org 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" Polling by MSI isn't necessarily faster than polling by SEV. Tests on hi1620 show hns3 100G NIC network throughput can improve from 25G to 27G if we disable MSI polling while running 16 netperf threads sending UDP packets in size 32KB. TX throughput can improve from 7G to 7.7G for single thread. The reason for the throughput improvement is that the latency to poll the completion of CMD_SYNC becomes smaller. After sending a CMD_SYNC in an empty cmd queue, typically we need to wait for 280ns using MSI polling. But we only need around 190ns after disabling MSI polling. This patch provides a command line option so that users can decide to use MSI polling or not based on their tests. Reviewed-by: Robin Murphy Signed-off-by: Barry Song --- -v5: add Robin's reviewed-by drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 5b40d535a7c8..7332251dd8cd 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -418,6 +418,11 @@ module_param(disable_bypass, bool, 0444); MODULE_PARM_DESC(disable_bypass, "Disable bypass streams such that incoming transactions from devices that are not attached to an iommu domain will report an abort back to the device and will not be allowed to pass through the SMMU."); +static bool disable_msipolling; +module_param(disable_msipolling, bool, 0444); +MODULE_PARM_DESC(disable_msipolling, + "Disable MSI-based polling for CMD_SYNC completion."); + enum pri_resp { PRI_RESP_DENY = 0, PRI_RESP_FAIL = 1, @@ -652,6 +657,7 @@ struct arm_smmu_device { #define ARM_SMMU_OPT_SKIP_PREFETCH (1 << 0) #define ARM_SMMU_OPT_PAGE0_REGS_ONLY (1 << 1) +#define ARM_SMMU_OPT_MSIPOLL (1 << 2) u32 options; struct arm_smmu_cmdq cmdq; @@ -992,8 +998,7 @@ static void arm_smmu_cmdq_build_sync_cmd(u64 *cmd, struct arm_smmu_device *smmu, * Beware that Hi16xx adds an extra 32 bits of goodness to its MSI * payload, so the write will zero the entire command on that platform. */ - if (smmu->features & ARM_SMMU_FEAT_MSI && - smmu->features & ARM_SMMU_FEAT_COHERENCY) { + if (smmu->options & ARM_SMMU_OPT_MSIPOLL) { ent.sync.msiaddr = q->base_dma + Q_IDX(&q->llq, prod) * q->ent_dwords * 8; } @@ -1332,8 +1337,7 @@ static int __arm_smmu_cmdq_poll_until_consumed(struct arm_smmu_device *smmu, static int arm_smmu_cmdq_poll_until_sync(struct arm_smmu_device *smmu, struct arm_smmu_ll_queue *llq) { - if (smmu->features & ARM_SMMU_FEAT_MSI && - smmu->features & ARM_SMMU_FEAT_COHERENCY) + if (smmu->options & ARM_SMMU_OPT_MSIPOLL) return __arm_smmu_cmdq_poll_until_msi(smmu, llq); return __arm_smmu_cmdq_poll_until_consumed(smmu, llq); @@ -3741,8 +3745,11 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu) if (reg & IDR0_SEV) smmu->features |= ARM_SMMU_FEAT_SEV; - if (reg & IDR0_MSI) + if (reg & IDR0_MSI) { smmu->features |= ARM_SMMU_FEAT_MSI; + if (coherent && !disable_msipolling) + smmu->options |= ARM_SMMU_OPT_MSIPOLL; + } if (reg & IDR0_HYP) smmu->features |= ARM_SMMU_FEAT_HYP; -- 2.27.0 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu