linux-kernel - Re: [PATCH] cpufreq: intel_pstate: Fix rounding of core

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Message-ID: <CAJZ5v0hEFp8sQH3iB6SUeVVEmdYA6ZK1kvc9NM+7sbS-LTW6nQ@mail.gmail.com>
Date:	Wed, 11 Jun 2014 20:28:49 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Doug Smythies <dsmythies@...us.net>
Cc:	Stratos Karafotis <stratosk@...aphore.gr>,
	linux-pm@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, viresh.kumar@...aro.org,
	dirk.j.brandewie@...el.com
Subject: Re: [PATCH] cpufreq: intel_pstate: Fix rounding of core_pct

On Wed, Jun 11, 2014 at 5:02 PM, Doug Smythies <dsmythies@...us.net> wrote:
>
> On 2104.06.11 07:08 Stratos Karafotis wrote:
>> On 11/06/2014 04:41 μμ, Doug Smythies wrote:
>>
>> No.
>>
>> The intent was only ever to round properly the pseudo floating point result of the divide.
>> It was much more important (ugh, well 4 times more) when FRACBITS was still 6, which also got changed to 8 in a recent patch.
>>
>
> Are you sure?
>
> Yes.
>
>> This rounding was very recently added.
>> As far as I can understand, I don't see the meaning of this rounding, as is.
>> Even if FRAC_BITS was 6, I think it would have almost no improvement in
>> calculations.
>
> Note: I had not seen this e-mail when I wrote a few minutes ago:
>
> You may be correct.
> If Dirk agrees, I will re-analyse the entire driver for rounding effects soon.

Well, can you please do it if that's not a problem?

Rafael
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