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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 E0370C4338F for ; Wed, 11 Aug 2021 02:16:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B873360EB9 for ; Wed, 11 Aug 2021 02:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231673AbhHKCRG (ORCPT ); Tue, 10 Aug 2021 22:17:06 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:17004 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231533AbhHKCRF (ORCPT ); Tue, 10 Aug 2021 22:17:05 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GktdT5F3Nzb0kW; Wed, 11 Aug 2021 10:13:01 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 11 Aug 2021 10:16:40 +0800 Received: from [10.174.179.0] (10.174.179.0) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 11 Aug 2021 10:16:40 +0800 Subject: Re: [PATCH RFC 2/8] iommu/arm-smmu-v3: Add and use static helper function arm_smmu_cmdq_issue_cmd_with_sync() To: Will Deacon CC: Robin Murphy , Joerg Roedel , linux-arm-kernel , iommu , linux-kernel References: <20210626110130.2416-1-thunder.leizhen@huawei.com> <20210626110130.2416-3-thunder.leizhen@huawei.com> <20210810182454.GB3296@willie-the-truck> From: "Leizhen (ThunderTown)" Message-ID: Date: Wed, 11 Aug 2021 10:16:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20210810182454.GB3296@willie-the-truck> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.0] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/8/11 2:24, Will Deacon wrote: > On Sat, Jun 26, 2021 at 07:01:24PM +0800, Zhen Lei wrote: >> The obvious key to the performance optimization of commit 587e6c10a7ce >> ("iommu/arm-smmu-v3: Reduce contention during command-queue insertion") is >> to allow multiple cores to insert commands in parallel after a brief mutex >> contention. >> >> Obviously, inserting as many commands at a time as possible can reduce the >> number of times the mutex contention participates, thereby improving the >> overall performance. At least it reduces the number of calls to function >> arm_smmu_cmdq_issue_cmdlist(). >> >> Therefore, function arm_smmu_cmdq_issue_cmd_with_sync() is added to insert >> the 'cmd+sync' commands at a time. >> >> Signed-off-by: Zhen Lei >> --- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 33 +++++++++++++-------- >> 1 file changed, 21 insertions(+), 12 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 2433d3c29b49ff2..a5361153ca1d6a4 100644 >> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >> @@ -858,11 +858,25 @@ static int arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, >> return arm_smmu_cmdq_issue_cmdlist(smmu, cmd, 1, false); >> } >> >> -static int arm_smmu_cmdq_issue_sync(struct arm_smmu_device *smmu) >> +static int __maybe_unused arm_smmu_cmdq_issue_sync(struct arm_smmu_device *smmu) >> { >> return arm_smmu_cmdq_issue_cmdlist(smmu, NULL, 0, true); >> } >> >> +static int arm_smmu_cmdq_issue_cmd_with_sync(struct arm_smmu_device *smmu, >> + struct arm_smmu_cmdq_ent *ent) >> +{ >> + u64 cmd[CMDQ_ENT_DWORDS]; >> + >> + if (arm_smmu_cmdq_build_cmd(cmd, ent)) { >> + dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x\n", >> + ent->opcode); >> + return -EINVAL; >> + } >> + >> + return arm_smmu_cmdq_issue_cmdlist(smmu, cmd, 1, true); >> +} > > This function is almost identical to arm_smmu_cmdq_issue_cmd(). How about > moving the guts out into a helper: > > static int __arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, > struct arm_smmu_cmdq_ent *ent, > bool sync); > > and then having arm_smmu_cmdq_issue_cmd_with_sync() and > arm_smmu_cmdq_issue_cmd() wrap that? OK, I will do it. How about remove arm_smmu_cmdq_issue_sync()? It's unused now. > > Will > . >