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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 9EB46C4167B for ; Wed, 9 Dec 2020 18:15:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D74423C1A for ; Wed, 9 Dec 2020 18:15:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732349AbgLISPj (ORCPT ); Wed, 9 Dec 2020 13:15:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:58714 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731866AbgLISPj (ORCPT ); Wed, 9 Dec 2020 13:15:39 -0500 Date: Wed, 9 Dec 2020 19:16:14 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1607537698; bh=Awgb97eqMBhLF2z692oQRlyuDrGF+9hPTYxSsdle5bA=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=b0PaQLP6use6Dz/Xo4q+WevXeigi0daf/C/knM3UQ5XhYuOFNjPo8xFgM2DSu3cZx GCMLSFEf1C/ASc63Chak8CwVO/V80jSRzdqDe2wZUWf1EXG17XlAx87NKAchGuL/20 XWG80R7mN+rWEbVOJytVmM5Khg4lTm2Vb/LYAt7Q= From: Greg Kroah-Hartman To: Saravana Kannan Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Len Brown , Ard Biesheuvel , Rob Herring , Frank Rowand , Marc Zyngier , Thomas Gleixner , Tomi Valkeinen , Laurent Pinchart , Grygorii Strashko , kernel-team@android.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Message-ID: References: <20201121020232.908850-1-saravanak@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201121020232.908850-1-saravanak@google.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Nov 20, 2020 at 06:02:15PM -0800, Saravana Kannan wrote: > The current implementation of fw_devlink is very inefficient because it > tries to get away without creating fwnode links in the name of saving > memory usage. Past attempts to optimize runtime at the cost of memory > usage were blocked with request for data showing that the optimization > made significant improvement for real world scenarios. > > We have those scenarios now. There have been several reports of boot > time increase in the order of seconds in this thread [1]. Several OEMs > and SoC manufacturers have also privately reported significant > (350-400ms) increase in boot time due to all the parsing done by > fw_devlink. > > So this patch series refactors fw_devlink to be more efficient. The key > difference now is the addition of support for fwnode links -- just a few > simple APIs. This also allows most of the code to be moved out of > firmware specific (DT mostly) code into driver core. > > This brings the following benefits: > - Instead of parsing the device tree multiple times (complexity was > close to O(N^3) where N in the number of properties) during bootup, > fw_devlink parses each fwnode node/property only once and creates > fwnode links. The rest of the fw_devlink code then just looks at these > fwnode links to do rest of the work. > > - Makes it much easier to debug probe issue due to fw_devlink in the > future. fw_devlink=on blocks the probing of devices if they depend on > a device that hasn't been added yet. With this refactor, it'll be very > easy to tell what that device is because we now have a reference to > the fwnode of the device. > > - Much easier to add fw_devlink support to ACPI and other firmware > types. A refactor to move the common bits from DT specific code to > driver core was in my TODO list as a prerequisite to adding ACPI > support to fw_devlink. This series gets that done. > > Laurent and Grygorii tested the v1 series and they saw boot time > improvment of about 12 seconds and 3 seconds, respectively. Now queued up to my tree. Note, I had to hand-apply patches 13 and 16 due to some reason (for 13, I have no idea, for 16 it was due to a previous patch applied to my tree that I cc:ed you on.) Verifying I got it all correct would be great :) thanks, greg k-h