From: Saravana Kannan <saravanak@google.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ard Biesheuvel <ardb@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Android Kernel Team <kernel-team@android.com>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-efi <linux-efi@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>
Subject: Re: [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time
Date: Wed, 4 Nov 2020 15:26:36 -0800 [thread overview]
Message-ID: <CAGETcx9LRj9s=VA4Eck1=xaSq3FhHMRzxRLr=pZehxsEb0NGHQ@mail.gmail.com> (raw)
In-Reply-To: <20201104232356.4038506-1-saravanak@google.com>
On Wed, Nov 4, 2020 at 3:23 PM Saravana Kannan <saravanak@google.com> 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!
>
> Thanks,
> Saravana
>
> [1] - https://lore.kernel.org/linux-pm/CAGETcx-aiW251dhEXT1GNb9bi6YcX8W=jLBrro5CnPuEjGL09g@mail.gmail.com/
Forgot the update this link in the cover letter. Here's a much better
link to the thread that discusses boot time regression:
https://lore.kernel.org/linux-omap/ea02f57e-871d-cd16-4418-c1da4bbc4696@ti.com/
-Saravana
next prev parent reply other threads:[~2020-11-04 23:28 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-04 23:23 [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 01/18] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" Saravana Kannan
2020-11-05 9:34 ` Greg Kroah-Hartman
2020-11-05 23:19 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 02/18] Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 03/18] Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 04/18] Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 05/18] Revert "of: platform: Batch fwnode parsing when adding all top level devices" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 06/18] Revert "driver core: fw_devlink: Add support for batching fwnode parsing" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 07/18] driver core: Add fwnode_init() Saravana Kannan
2020-11-05 9:36 ` Greg Kroah-Hartman
2020-11-05 23:20 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 08/18] driver core: Add fwnode link support Saravana Kannan
2020-11-16 15:51 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 09/18] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links Saravana Kannan
2020-11-16 15:57 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 10/18] device property: Add fwnode_is_ancestor_of() Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 11/18] driver core: Redefine the meaning of fwnode_operations.add_links() Saravana Kannan
2020-11-16 16:16 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 12/18] driver core: Add fw_devlink_parse_fwtree() Saravana Kannan
2020-11-16 16:25 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 13/18] driver core: Add fwnode_get_next_parent_dev() helper function Saravana Kannan
2020-11-16 16:27 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 14/18] driver core: Use device's fwnode to check if it is waiting for suppliers Saravana Kannan
2020-11-16 16:34 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 15/18] of: property: Update implementation of add_links() to create fwnode links Saravana Kannan
2020-11-05 9:42 ` Greg Kroah-Hartman
2020-11-05 23:25 ` Saravana Kannan
2020-11-06 1:24 ` Saravana Kannan
2020-11-06 7:22 ` Greg Kroah-Hartman
2020-11-06 7:41 ` Saravana Kannan
2020-11-06 7:51 ` Greg Kroah-Hartman
2020-11-06 8:29 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 16/18] efi: " Saravana Kannan
2020-11-05 9:43 ` Greg Kroah-Hartman
2020-11-05 23:27 ` Saravana Kannan
2020-11-06 6:45 ` Greg Kroah-Hartman
2020-11-04 23:23 ` [PATCH v1 17/18] driver core: Add helper functions to convert fwnode links to device links Saravana Kannan
2020-11-05 9:43 ` Greg Kroah-Hartman
2020-11-05 23:32 ` Saravana Kannan
2020-11-06 7:24 ` Greg Kroah-Hartman
2020-11-06 7:43 ` Saravana Kannan
2020-11-16 16:57 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 18/18] driver core: Refactor fw_devlink feature Saravana Kannan
2020-11-04 23:26 ` Saravana Kannan [this message]
2020-11-06 5:09 ` [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time Laurent Pinchart
2020-11-06 8:36 ` Saravana Kannan
2020-11-06 12:46 ` Grygorii Strashko
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