netdev - Re: [PATCH v4 0/3] thermal/netlink/intel_hfi: Enable HFI feature only when required

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Message-ID: <CAJZ5v0jGpzn8kO8P8w_QUvo7MaaVMpURDZjzcdB2DjPkRnSmBg@mail.gmail.com>
Date: Thu, 29 Feb 2024 17:24:15 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org, 
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, 
	Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Jiri Pirko <jiri@...nulli.us>, Johannes Berg <johannes@...solutions.net>, 
	Florian Westphal <fw@...len.de>, netdev@...r.kernel.org
Subject: Re: [PATCH v4 0/3] thermal/netlink/intel_hfi: Enable HFI feature only
 when required

On Thu, Feb 29, 2024 at 5:13 PM Stanislaw Gruszka
<stanislaw.gruszka@...ux.intel.com> wrote:
>
> On Thu, Feb 29, 2024 at 04:18:50PM +0100, Rafael J. Wysocki wrote:
> > On Mon, Feb 12, 2024 at 5:16 PM Stanislaw Gruszka
> > <stanislaw.gruszka@...ux.intel.com> wrote:
> > >
> > > The patchset introduces a new genetlink family bind/unbind callbacks
> > > and thermal/netlink notifications, which allow drivers to send netlink
> > > multicast events based on the presence of actual user-space consumers.
> > > This functionality optimizes resource usage by allowing disabling
> > > of features when not needed.
> > >
> > > Then implement the notification mechanism in the intel_hif driver,
> > > it is utilized to disable the Hardware Feedback Interface (HFI)
> > > dynamically. By implementing a thermal genl notify callback, the driver
> > > can now enable or disable the HFI based on actual demand, particularly
> > > when user-space applications like intel-speed-select or Intel Low Power
> > > daemon utilize events related to performance and energy efficiency
> > > capabilities.
> > >
> > > On machines where Intel HFI is present, but there are no user-space
> > > components installed, we can save tons of CPU cycles.
> > >
> > > Changes v3 -> v4:
> > >
> > > - Add 'static inline' in patch2
> > >
> > > Changes v2 -> v3:
> > >
> > > - Fix unused variable compilation warning
> > > - Add missed Suggested by tag to patch2
> > >
> > > Changes v1 -> v2:
> > >
> > > - Rewrite using netlink_bind/netlink_unbind callbacks.
> > >
> > > - Minor changelog tweaks.
> > >
> > > - Add missing check in intel hfi syscore resume (had it on my testing,
> > > but somehow missed in post).
> > >
> > > - Do not use netlink_has_listeners() any longer, use custom counter instead.
> > > To keep using netlink_has_listners() would be required to rearrange
> > > netlink_setsockopt() and possibly netlink_bind() functions, to call
> > > nlk->netlink_bind() after listeners are updated. So I decided to custom
> > > counter. This have potential issue as thermal netlink registers before
> > > intel_hif, so theoretically intel_hif can miss events. But since both
> > > are required to be kernel build-in (if CONFIG_INTEL_HFI_THERMAL is
> > > configured), they start before any user-space.
> > >
> > > v1: https://lore.kernel.org/linux-pm/20240131120535.933424-1-stanislaw.gruszka@linux.intel.com//
> > > v2: https://lore.kernel.org/linux-pm/20240206133605.1518373-1-stanislaw.gruszka@linux.intel.com/
> > > v3: https://lore.kernel.org/linux-pm/20240209120625.1775017-1-stanislaw.gruszka@linux.intel.com/
> > >
> > > Stanislaw Gruszka (3):
> > >   genetlink: Add per family bind/unbind callbacks
> > >   thermal: netlink: Add genetlink bind/unbind notifications
> > >   thermal: intel: hfi: Enable interface only when required
> > >
> > >  drivers/thermal/intel/intel_hfi.c | 95 +++++++++++++++++++++++++++----
> > >  drivers/thermal/thermal_netlink.c | 40 +++++++++++--
> > >  drivers/thermal/thermal_netlink.h | 26 +++++++++
> > >  include/net/genetlink.h           |  4 ++
> > >  net/netlink/genetlink.c           | 30 ++++++++++
> > >  5 files changed, 180 insertions(+), 15 deletions(-)
> > >
> > > --
> >
> > What tree is this based on?
>
> v5: https://patchwork.kernel.org/project/linux-pm/list/?series=829159
> it's on top of linux-pm master, but require additional net dependency,
> which can be added by:
>
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux.git for-thermal-genetlink-family-bind-unbind-callbacks
> git merge FETCH_HEAD
>
> and will be merged mainline in the next merge window.
> So at this point would be probably better just wait for 6.9-rc1
> when the dependency will be in the mainline, before applying this set.

And that's what's going to happen, unless I have any additional
comments on the patches.

Thanks!