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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 DB99EC46460 for ; Wed, 15 Aug 2018 10:23:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F59721581 for ; Wed, 15 Aug 2018 10:23:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F59721581 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729171AbeHONPS (ORCPT ); Wed, 15 Aug 2018 09:15:18 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:60845 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728921AbeHONPR (ORCPT ); Wed, 15 Aug 2018 09:15:17 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id C226784E9ED0C; Wed, 15 Aug 2018 18:23:28 +0800 (CST) Received: from localhost (10.177.23.164) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.399.0; Wed, 15 Aug 2018 18:23:22 +0800 From: Zhen Lei To: Robin Murphy , Will Deacon , Joerg Roedel , linux-arm-kernel , iommu , linux-kernel CC: Zhen Lei , LinuxArm , Hanjun Guo , Libin , "John Garry" Subject: [PATCH v3 0/2] bugfix and optimization about CMD_SYNC Date: Wed, 15 Aug 2018 18:23:00 +0800 Message-ID: <1534328582-17664-1-git-send-email-thunder.leizhen@huawei.com> X-Mailer: git-send-email 1.9.5.msysgit.0 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v2 -> v3: Although I have no data to show how many performance will be impacted because of arm_smmu_cmdq_build_cmd is protected by spinlock. But it's clear that the performance is bound to drop, a memset operation and a complicate switch..case in the function arm_smmu_cmdq_build_cmd. v1 -> v2: 1. move the call to arm_smmu_cmdq_build_cmd into the critical section, and keep itself unchange. 2. Although patch2 can make sure no two CMD_SYNCs will be adjacent, but patch1 is still needed, see below: cpu0 cpu1 cpu2 msidata=0 msidata=1 insert cmd1 insert a TLBI command insert cmd0 smmu execute cmd1 smmu execute TLBI smmu execute cmd0 poll timeout, because msidata=1 is overridden by cmd0, that means VAL=0, sync_idx=1. Zhen Lei (2): iommu/arm-smmu-v3: fix unexpected CMD_SYNC timeout iommu/arm-smmu-v3: avoid redundant CMD_SYNCs if possible drivers/iommu/arm-smmu-v3.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) -- 1.8.3