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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68AA5C25B6F for ; Fri, 27 Oct 2023 06:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233035AbjJ0GJS (ORCPT ); Fri, 27 Oct 2023 02:09:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229633AbjJ0GJQ (ORCPT ); Fri, 27 Oct 2023 02:09:16 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1EB41B2; Thu, 26 Oct 2023 23:09:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1698386954; x=1729922954; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=+DrVyO/lmmzNiD355grMg157EiJ4H0MKLPJHIYM0VSM=; b=Hekwgo6jRGDrzcq2saqRM+zqvUIqGMPoYzpyIbMmqbpVLIgLeWr1H5nr pneDqZWAWgR/r6D5BxyPFCRNB0tlu+CDx+k/0mvOBusG46FR7rX9IQelS FS3D1zLWTuVU9wJ55oDA62BLVaDJeaZXbYAfC7XmoCQtcX4nV50xljYLV yhs0aDd961PgIKs4vrp8iV6XkI0+yIGrm/wS5aDe+Lta26qzT0jD1wv5Q CxWEWNOkZjFV/+tWedHMKCY4Pl8PRCaeruxzQPEMR2ITfgS7Nwd65TzBr YgBsctdovK7a2+zU7M0goKeJUtRUugRR5SN6K4NI6A0NYve70ytf1Xxme w==; X-IronPort-AV: E=McAfee;i="6600,9927,10875"; a="418823669" X-IronPort-AV: E=Sophos;i="6.03,255,1694761200"; d="scan'208";a="418823669" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2023 23:09:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.03,255,1694761200"; d="scan'208";a="708126" Received: from jiaqingh-mobl.ccr.corp.intel.com (HELO [10.93.11.63]) ([10.93.11.63]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2023 23:08:35 -0700 Message-ID: Date: Fri, 27 Oct 2023 14:09:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] iommu: Introduce a rb_tree for looking up device Content-Language: en-US To: Baolu Lu , joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, dwmw2@infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev Cc: jacob.jun.pan@linux.intel.com, kevin.tian@intel.com, yi.y.sun@intel.com, kvm@vger.kernel.org References: <20231024084124.11155-1-jiaqing.huang@intel.com> <5a4c169d-8e42-4609-87db-8b68f04bb0fe@linux.intel.com> From: "Huang, Jiaqing" In-Reply-To: <5a4c169d-8e42-4609-87db-8b68f04bb0fe@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/24/2023 7:58 PM, Baolu Lu wrote: > On 2023/10/24 16:41, Huang Jiaqing wrote: >> The existing IO page fault handler locates the PCI device by calling >> pci_get_domain_bus_and_slot(), which searches the list of all PCI >> devices until the desired PCI device is found. This is inefficient >> because the algorithm efficiency of searching a list is O(n). In the >> critical path of handling an IO page fault, this is not performance >> friendly given that I/O page fault handling patch is performance >> critical, and parallel heavy dsa_test may cause cpu stuck due to >> the low efficiency and lock competition in current path. >> >> To improve the performance of the IO page fault handler, replace >> pci_get_domain_bus_and_slot() with a local red-black tree. A red-black >> tree is a self-balancing binary search tree, which means that the >> average time complexity of searching a red-black tree is O(log(n)). This >> is significantly faster than O(n), so it can significantly improve the >> performance of the IO page fault handler. >> >> In addition, we can only insert the affected devices (those that have IO >> page fault enabled) into the red-black tree. This can further improve >> the performance of the IO page fault handler. >> >> This series depends on "deliver page faults to user space" patch-set: >> https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@linux.intel.com/ >> > > The note above is not part of the commit message, and should be placed > below the tear line or in the cover letter, if there is one. Will fix, thanks for catching! BRs, Jiaqing