Re: [PATCH v5] PM: QoS: Introduce boot parameter pm_qos_resume_latency_us

[Rafael J. Wysocki]

On Mon, Jun 1, 2026 at 8:55 PM Aaron Tomlin <atomlin@xxxxxxxxxxx> wrote:
>
> On Sun, Apr 26, 2026 at 12:01:27PM -0400, Aaron Tomlin wrote:
> > This patch introduces the pm_qos_resume_latency_us kernel boot
> > parameter, which allows users to specify distinct resume latency
> > constraints for specific CPU ranges.
> >
> >       Syntax: pm_qos_resume_latency_us=range:value;range:value...
> >
> > This boot parameter mirrors the sysfs interface behaviour: the special
> > string "n/a" imposes a 0us latency constraint (polling), while the
> > integer 0 removes the constraint entirely.
>
> Hi Greg, Rafael, Danilo, Pavel, Len,
>
> It has been over a month since I submitted this, so I just wanted to gently
> ping this thread.
>
> As a quick reminder, this parameter is highly beneficial for deployments
> that prefer to establish strict latency constraints early in the boot
> process, eliminating the need to rely on custom user-space tooling later
> on.
>
> Patch link: https://lore.kernel.org/lkml/20260426160127.292486-1-atomlin@xxxxxxxxxxx/
>
> Please let me know if you have any conceptual concerns with this approach,
> if any further adjustments are required,

IMV it would be better to call the new command line arg something like
"cpu_idle_exit_latency_us" to make it clear what it is about.

Also, generally speaking, it should be part of cpuidle rather than the
generic QoS code that also applies to devices other than CPUs.

> or if you simply need me to rebase and resend this against the latest power management tree.

And that too.

Thanks!