From patchwork Thu Aug 27 09:29:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Song Bao Hua (Barry Song)" X-Patchwork-Id: 11740457 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 989C413B6 for ; Thu, 27 Aug 2020 09:33:26 +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 71BA622CF8 for ; Thu, 27 Aug 2020 09:33:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BbhR47Yu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71BA622CF8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=hisilicon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: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:List-Owner; bh=XUzjWiwPbKOQPFWeJmOXORpjoWY3rIrTlSGRzzspbOg=; b=BbhR47Yu5FPAs3aQC8gUGd/8N itm4kYqb2LyavhtTESK1uqpjyCBAocw6lzRDLqPnqK4Z+jNHJN8Cx4fRY/7Dk6BOdBg9kONhyhqoe e7G48mSUr91gUutFpSX524w47pzAsVrWww2HfobI3npoZ+ErxyiRKtz2x5lIViNLyBviQumcDG8cY B7fW8Zo1TGSX5cvftyRZbG59zVCr6rR2V+xhqh7slC5KThKTzJzK7MLqNcqJ1N7+oxEDt89v40cdb iOu+8PXvlGUxVOxRQfLEpAN7kdPwAxuS2eB8+0Y/zNg3mxA3YJWxSO/zmfywfST4HYJFeLbc3kno5 3h4HWcTSA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBEHS-0006gw-Nz; Thu, 27 Aug 2020 09:33:14 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191] helo=huawei.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBEHK-0006cE-7e for linux-arm-kernel@lists.infradead.org; Thu, 27 Aug 2020 09:33:07 +0000 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200827_053306_588766_D06301CE X-CRM114-Status: GOOD ( 13.81 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [45.249.212.191 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 SPF_HELO_PASS SPF: HELO matches SPF record 0.0 RCVD_IN_MSPIKE_H4 RBL: Very Good reputation (+4) [45.249.212.191 listed in wl.mailspike.net] 0.0 RCVD_IN_MSPIKE_WL Mailspike good senders 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: Barry Song , robin.murphy@arm.com, joro@8bytes.org, will@kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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;