linux-kernel - Re: [PATCH 2/2] x86/tsc: set LAPIC timer frequency to crystal clock frequency

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Message-ID: <CAD8Lp44ZaifPf+809BzbLg=9ijsRsE=7JMVpXkqRenY9radpZA@mail.gmail.com>
Date:   Tue, 23 Apr 2019 11:06:36 +0800
From:   Daniel Drake <drake@...lessm.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        hpa@...or.com, x86@...nel.org,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Len Brown <len.brown@...el.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        Linux Upstreaming Team <linux@...lessm.com>
Subject: Re: [PATCH 2/2] x86/tsc: set LAPIC timer frequency to crystal clock frequency

On Mon, Apr 22, 2019 at 8:04 PM Ingo Molnar <mingo@...nel.org> wrote:
> Minor style nit: the parentheses are unnecessary, integer expressions
> like this are evaluated left to right and multiplication and division has
> the same precedence.

Fair point, although the same could be said for cpu_khz_from_msr().

> But it might also make sense to actually store crystal_mhz instead of
> crystal_khz, because both CPUID 15H and 16H provides MHz values.
>
> That way the above expression would simplify to:
>
>         lapic_timer_frequency = crystal_mhz / HZ;

Wouldn't it be
        lapic_timer_frequency = crystal_mhz * 1000000 / HZ;
?

Thanks
Daniel