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=-3.8 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,URIBL_BLOCKED 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 9EAA3C2D0A3 for ; Fri, 6 Nov 2020 05:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3239C208B3 for ; Fri, 6 Nov 2020 05:09:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ezicyJe3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725842AbgKFFJp (ORCPT ); Fri, 6 Nov 2020 00:09:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbgKFFJp (ORCPT ); Fri, 6 Nov 2020 00:09:45 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24F14C0613CF; Thu, 5 Nov 2020 21:09:45 -0800 (PST) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 9BE333D; Fri, 6 Nov 2020 06:09:43 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1604639383; bh=72/KUrhMBGIoUetzc6guWYFWopnI5c0uHM8v4HvuRPc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ezicyJe3TH8q8Ejj8OJ4o9ti4tZBl8nP0nWdq3cOvkoDRGPrmeo4/M6VqLD7PYK44 9UF8TtdfQpkYyEDrqEMG7KTEdsRoZGs5g8ssxNGacB5T1tVM05IYsjcpRedN3Auqs2 QN7HhTIBAHZG/EsFOmyKA0hho5RSOtc5Rn93tW6Y= Date: Fri, 6 Nov 2020 07:09:40 +0200 From: Laurent Pinchart To: Saravana Kannan 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 , 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 v1 00/18] Refactor fw_devlink to significantly improve boot time Message-ID: <20201106050940.GG16469@pendragon.ideasonboard.com> References: <20201104232356.4038506-1-saravanak@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201104232356.4038506-1-saravanak@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org 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. 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 :-) Tested-by: Laurent Pinchart > [1] - https://lore.kernel.org/linux-pm/CAGETcx-aiW251dhEXT1GNb9bi6YcX8W=jLBrro5CnPuEjGL09g@mail.gmail.com/ > > Saravana Kannan (18): > Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" > Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" > Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" > Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" > Revert "of: platform: Batch fwnode parsing when adding all top level devices" > Revert "driver core: fw_devlink: Add support for batching fwnode parsing" > driver core: Add fwnode_init() > driver core: Add fwnode link support > driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links > device property: Add fwnode_is_ancestor_of() > driver core: Redefine the meaning of fwnode_operations.add_links() > driver core: Add fw_devlink_parse_fwtree() > driver core: Add fwnode_get_next_parent_dev() helper function > driver core: Use device's fwnode to check if it is waiting for suppliers > of: property: Update implementation of add_links() to create fwnode links > efi: Update implementation of add_links() to create fwnode links > driver core: Add helper functions to convert fwnode links to device links > driver core: Refactor fw_devlink feature > > drivers/acpi/property.c | 2 +- > drivers/acpi/scan.c | 2 +- > drivers/base/core.c | 584 +++++++++++++++++++++----------- > drivers/base/property.c | 27 ++ > drivers/base/swnode.c | 2 +- > drivers/firmware/efi/efi-init.c | 31 +- > drivers/of/dynamic.c | 1 + > drivers/of/platform.c | 2 - > drivers/of/property.c | 150 +++----- > include/linux/device.h | 10 +- > include/linux/fwnode.h | 66 ++-- > include/linux/of.h | 2 +- > include/linux/property.h | 2 + > kernel/irq/irqdomain.c | 2 +- > 14 files changed, 490 insertions(+), 393 deletions(-) -- Regards, Laurent Pinchart