From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Doug Smythies" Subject: RE: [PATCH] cpufreq: intel_pstate: Fix rounding of core_pct Date: Wed, 11 Jun 2014 08:02:19 -0700 Message-ID: <00a001cf8586$24eb5c70$6ec21550$@net> References: <1402490012-19969-1-git-send-email-stratosk@semaphore.gr> <009b01cf857a$d5032090$7f0961b0$@net> <539862DB.9060905@semaphore.gr> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cmta18.telus.net ([209.171.16.91]:41974 "EHLO cmta18.telus.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751049AbaFKPCX convert rfc822-to-8bit (ORCPT ); Wed, 11 Jun 2014 11:02:23 -0400 In-Reply-To: <539862DB.9060905@semaphore.gr> Content-Language: en-ca Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: 'Stratos Karafotis' Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, dirk.j.brandewie@intel.com On 2104.06.11 07:08 Stratos Karafotis wrote: > On 11/06/2014 04:41 =CE=BC=CE=BC, Doug Smythies wrote: >=20 > No. >=20 > 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. >=20 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 effect= s 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. =2E.. Doug