From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Saravana Kannan <saravanak@google.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.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>,
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 v2 00/17] Refactor fw_devlink to significantly improve boot time
Date: Thu, 10 Dec 2020 10:26:28 +0100 [thread overview]
Message-ID: <X9HpxMOgzlCcVI7p@kroah.com> (raw)
In-Reply-To: <CAGETcx_5_=VKxbTddtG4u7p0yhCTdkr746fToPtPecEZcE1ncg@mail.gmail.com>
On Wed, Dec 09, 2020 at 12:24:32PM -0800, Saravana Kannan wrote:
> On Wed, Dec 9, 2020 at 10:15 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > 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 :)
>
> A quick diff of drivers/base/core.c between driver-core-testing and my
> local tree doesn't show any major diff (only some unrelated comment
> fixes). So, it looks fine.
>
> The patch 13 conflict is probably due to having to rebase the v2
> series on top of this:
> https://lore.kernel.org/lkml/20201104205431.3795207-1-saravanak@google.com/
>
> And looks like Patch 16 was handled fine.
Great, thanks for verifying!
greg k-h
prev parent reply other threads:[~2020-12-10 9:25 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-21 2:02 [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 01/17] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 02/17] Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 03/17] Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 04/17] Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 05/17] Revert "of: platform: Batch fwnode parsing when adding all top level devices" Saravana Kannan
2020-12-07 22:18 ` Rob Herring
2020-11-21 2:02 ` [PATCH v2 06/17] Revert "driver core: fw_devlink: Add support for batching fwnode parsing" Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 07/17] driver core: Add fwnode_init() Saravana Kannan
2020-12-06 7:26 ` Leon Romanovsky
2020-12-07 19:25 ` Saravana Kannan
2020-12-07 19:53 ` Leon Romanovsky
2020-12-07 20:36 ` Saravana Kannan
2020-12-08 6:34 ` Leon Romanovsky
2020-12-07 22:20 ` Rob Herring
2020-11-21 2:02 ` [PATCH v2 08/17] driver core: Add fwnode link support Saravana Kannan
2020-12-06 7:48 ` Leon Romanovsky
2020-12-07 19:25 ` Saravana Kannan
2020-12-07 19:56 ` Leon Romanovsky
2020-12-07 22:21 ` Rob Herring
2020-11-21 2:02 ` [PATCH v2 09/17] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 10/17] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev() Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 11/17] driver core: Redefine the meaning of fwnode_operations.add_links() Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 12/17] driver core: Add fw_devlink_parse_fwtree() Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 13/17] driver core: Use device's fwnode to check if it is waiting for suppliers Saravana Kannan
2022-06-27 11:42 ` Abel Vesa
2022-06-27 22:30 ` Saravana Kannan
2022-06-28 15:24 ` Abel Vesa
2022-06-28 15:44 ` Abel Vesa
2022-06-28 15:55 ` Abel Vesa
2022-06-28 18:09 ` Saravana Kannan
2023-01-05 14:47 ` Dmitry Baryshkov
2020-11-21 2:02 ` [PATCH v2 14/17] of: property: Update implementation of add_links() to create fwnode links Saravana Kannan
2020-12-07 22:37 ` Rob Herring
2020-11-21 2:02 ` [PATCH v2 15/17] efi: " Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Saravana Kannan
2020-11-23 16:00 ` [driver core] 95f755a4ef: will-it-scale.per_process_ops 2.2% improvement kernel test robot
2020-12-11 14:11 ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Qian Cai
2020-12-11 16:34 ` Robin Murphy
2020-12-11 17:51 ` Saravana Kannan
2020-12-11 18:03 ` Marc Zyngier
2020-12-11 18:20 ` Saravana Kannan
2020-12-11 19:07 ` Marc Zyngier
2020-12-11 22:29 ` Saravana Kannan
2020-12-29 3:34 ` Michael Walle
2021-01-05 19:00 ` Saravana Kannan
2021-01-05 21:03 ` Michael Walle
2021-01-06 23:29 ` Saravana Kannan
2020-11-21 2:02 ` [PATCH v2 17/17] driver core: Delete pointless parameter in fwnode_operations.add_links Saravana Kannan
2020-12-07 22:38 ` Rob Herring
2020-11-24 8:29 ` [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Tomi Valkeinen
2020-11-24 17:25 ` Saravana Kannan
2020-12-03 19:05 ` Saravana Kannan
2020-12-09 18:16 ` Greg Kroah-Hartman
2020-12-09 20:24 ` Saravana Kannan
2020-12-10 9:26 ` Greg Kroah-Hartman [this message]
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