linux-kernel - Re: [PATCH 02/22 v2] cpufreq/acpi-cpufreq: drop rdmsr_on

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Message-ID: <20161128095430.GB3288@vireshk-i7>
Date:   Mon, 28 Nov 2016 15:24:30 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, rt@...utronix.de, tglx@...utronix.de,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 02/22 v2] cpufreq/acpi-cpufreq: drop rdmsr_on_cpus() usage

On 28-11-16, 10:52, Sebastian Andrzej Siewior wrote:
> The online / pre_down callback is invoked on the target CPU since commit
> 1cf4f629d9d2 ("cpu/hotplug: Move online calls to hotplugged cpu") which means
> for the hotplug callback we can use rmdsrl() instead of rdmsr_on_cpus().
> 
> This leaves us with set_boost() as the only user which still needs to
> read/write the MSR on different CPUs. There is no point in doing that
> update on all cpus with the read modify write magic via per cpu data. We
> simply can issue a function call on all online CPUs which also means that we
> need half that many IPIs.
> 
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: linux-pm@...r.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
> v1…v2: rebase ontop of the previous patch.

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh