Re: [PATCH 1/6] cpufreq: acpi: Don't enable boost on policy exit

From: Viresh Kumar
Date: Thu Apr 24 2025 - 03:15:20 EST


On 23-04-25, 16:14, Rafael J. Wysocki wrote:
> Even after commit 2b16c631832d, the code removed by this patch does a
> useful thing. Namely, it clears the boost-disable bit in the MSR so
> that the offline CPU doesn't prevent online CPUs from getting the
> boost (in case the boost settings change after it has been taken
> offline).

I didn't understand this part earlier (and even now). How does a CPU
with boost-disabled, prevents others from boosting ? I have tried
looking at git logs, and still don't understand it :(

Also, IIUC this and the boost-enabling at init() only happens for one
CPU in a policy, as init() and exit() are only called for the first
and last CPU of a policy. So if a policy has multiple CPUs, we aren't
touching boost states of other CPUs at init/exit.

And yes, this patch isn't mandatory at all for the

> Moreover, without the $subject patch, the change made by the next one
> will cause the boost setting in the MSR to get back in sync with
> policy->boost_enabled during online AFAICS, so why exactly is the
> $subject patch needed?

Right, this is merely a cleanup patch and isn't really required for
the next patch to make it work.

--
viresh