From: "Doug Smythies" <dsmythies@telus.net>
To: 'Stratos Karafotis' <stratosk@semaphore.gr>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
rjw@rjwysocki.net, viresh.kumar@linaro.org,
dirk.j.brandewie@intel.com
Subject: RE: [PATCH] cpufreq: intel_pstate: Fix rounding of core_pct
Date: Wed, 11 Jun 2014 08:02:19 -0700 [thread overview]
Message-ID: <00a001cf8586$24eb5c70$6ec21550$@net> (raw)
In-Reply-To: <539862DB.9060905@semaphore.gr>
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.
When FRACBITS was 6 there were subtle cases where the driver would get stuck, and not make a final pstate change, with the default PID gains.
Other things have changed, and the analysis needs to be re-done.
... Doug
next prev parent reply other threads:[~2014-06-11 15:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-11 12:33 [PATCH] cpufreq: intel_pstate: Fix rounding of core_pct Stratos Karafotis
2014-06-11 13:41 ` Doug Smythies
2014-06-11 14:08 ` Stratos Karafotis
2014-06-11 15:02 ` Doug Smythies [this message]
2014-06-11 18:28 ` Rafael J. Wysocki
2014-06-11 21:40 ` Doug Smythies
2014-06-11 21:45 ` Rafael J. Wysocki
2014-06-12 6:56 ` Doug Smythies
2014-06-11 20:20 ` Stratos Karafotis
2014-06-11 21:15 ` Doug Smythies
2014-06-12 14:35 ` Stratos Karafotis
2014-06-12 20:03 ` Rafael J. Wysocki
2014-06-13 6:49 ` Doug Smythies
2014-06-13 17:39 ` Stratos Karafotis
2014-06-13 13:48 ` Dirk Brandewie
2014-06-13 14:36 ` Doug Smythies
2014-06-13 16:56 ` Stratos Karafotis
2014-06-11 14:27 ` Doug Smythies
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