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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 A6D98C388F2 for ; Fri, 6 Nov 2020 08:36:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AC7621734 for ; Fri, 6 Nov 2020 08:36:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Ji/jXL4w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726711AbgKFIgq (ORCPT ); Fri, 6 Nov 2020 03:36:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44848 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726692AbgKFIgp (ORCPT ); Fri, 6 Nov 2020 03:36:45 -0500 Received: from mail-yb1-xb43.google.com (mail-yb1-xb43.google.com [IPv6:2607:f8b0:4864:20::b43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86732C0613D3 for ; Fri, 6 Nov 2020 00:36:45 -0800 (PST) Received: by mail-yb1-xb43.google.com with SMTP id i193so468094yba.1 for ; Fri, 06 Nov 2020 00:36:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=qEZLCwayVmjTSz55WLFDrASQyKwm9AzKbv8zrefCiDk=; b=Ji/jXL4wApkUI69Y5av8UFEa6ZvMG8Mm7sMdeBuZf7EoU4V1ZJLIvyslti7xbYYgOo 7sI5169sAiOnVjscRjwLSG5mTCDgJbsvvoyW7NaM+rXP+TANNYM9GzJTJeHzh5IJBSn6 jCu4ranqabbyvqfRRUp8VUmP12hOGnUWANJ2MHUcQuqSD+QuRogFeUpnHgYeTln5Ymb2 IxW851j1Otp0qXE2KbajHox2eLThi38VBbZU7+cZkmlqcN1NRpsNCkHTGxZofwDuILfd YJVqD/sCpYRPLK+Qa+6GsSNblgKHxW6x/FkEn9nScueY9kHi8mFdGrFX2iHrBlCcY0aX 0Zzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=qEZLCwayVmjTSz55WLFDrASQyKwm9AzKbv8zrefCiDk=; b=ocr/bi0FSTspjjBWEhPV02rG4BMxT5VgRfx+5V30b/K+3FipGDFY63JY4jwaxH6t3A 3+w6/nrXCHaG8mWd+4Ff2tPRJM8JlFM5vQePKGX05fRKhWTKq0b2OodOghpKJN7yCgAS Re3nyU7aWz/311MYpYNnZjiz6RD5QzxKELv9qQphVYj8MV6KEA3/h3ZY/+9Vq1YK+feu pQuXGiT4DWuEeG5/DFLAlbFjz4eBmeAk42duhioO0/oAh6EYsTtT24dOa+kNBa/AaKpe 7B3jbzNUtcomhiqaaDkcIG1kiK7Cmv5HYVArYAPOZ7yCaKp3EKixT8yq6p2nQlZvXDTQ tJaQ== X-Gm-Message-State: AOAM53194XISEed1Qf8a3YlAd1gZaJS5aHqQ8hxY0XSt9fY+XY3l2eei 8Q0cayKjJ1CV8iUOwkM/2dGTIPAyG20nrFut/9eV3g== X-Google-Smtp-Source: ABdhPJzvDcNdXHjO7nYfSMx7aYo6WWdRNoKpDm3K2m0Ae6MfNyULyjym/ptGih8ndA11+PnN2rHt+iT8lQNTMQ3Kip0= X-Received: by 2002:a25:d2c5:: with SMTP id j188mr1358442ybg.32.1604651804489; Fri, 06 Nov 2020 00:36:44 -0800 (PST) MIME-Version: 1.0 References: <20201104232356.4038506-1-saravanak@google.com> <20201106050940.GG16469@pendragon.ideasonboard.com> In-Reply-To: <20201106050940.GG16469@pendragon.ideasonboard.com> From: Saravana Kannan Date: Fri, 6 Nov 2020 00:36:08 -0800 Message-ID: Subject: Re: [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time To: Laurent Pinchart Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Len Brown , Greg Kroah-Hartman , Ard Biesheuvel , Rob Herring , Frank Rowand , Marc Zyngier , Thomas Gleixner , Tomi Valkeinen , Grygorii Strashko , Android Kernel Team , ACPI Devel Maling List , LKML , linux-efi , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Thu, Nov 5, 2020 at 9:09 PM Laurent Pinchart wrote: > > Hi Saravana, > > Thank you for working on this ! > > On Wed, Nov 04, 2020 at 03:23:37PM -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. > > > > Tomi/Laurent/Grygorii, > > > > If you can test this series, that'd be great! > > I gave it a try, rebasing my branch from v5.9 to v5.10-rc2 first. On > v5.10-rc2 the kernel dies when booting due to a deadlock (reported by > lockdep, so hopefully not too hard to debug). *sigh*. Fortunately, it > dies after the fw_devlink initialization, so I can still report results. Phew! For a sec I thought you said fw_devlink was causing a deadlock. > > Before your series: > > [ 0.743065] cpuidle: using governor menu > [ 13.350259] No ATAGs? > > With your series applied: > > [ 0.722670] cpuidle: using governor menu > [ 1.135859] No ATAGs? > > That's a very clear improvement :-) Thanks for testing. Great to hear it's helping! > Tested-by: Laurent Pinchart I'll add it to my v2 series. -Saravana