From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1425505AbcBSIJc (ORCPT ); Fri, 19 Feb 2016 03:09:32 -0500 Received: from foss.arm.com ([217.140.101.70]:44377 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424890AbcBSIJa (ORCPT ); Fri, 19 Feb 2016 03:09:30 -0500 Date: Fri, 19 Feb 2016 08:09:17 +0000 From: Juri Lelli To: "Rafael J. Wysocki" Cc: Linux PM list , Peter Zijlstra , Ingo Molnar , Linux Kernel Mailing List , Srinivas Pandruvada , Viresh Kumar , Steve Muckle , Thomas Gleixner , "Rafael J. Wysocki" Subject: Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering utilization update callbacks Message-ID: <20160219080917.GE22643@pablo> References: <3071836.JbNxX8hU6x@vostro.rjw.lan> <2044559.7ypXocW9OZ@vostro.rjw.lan> <3499355.2JlaSruvOa@vostro.rjw.lan> <16016177.YFqb4gVNBo@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rafael, On 18/02/16 21:22, Rafael J. Wysocki wrote: > On Mon, Feb 15, 2016 at 10:47 PM, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki > > [...] > > So if anyone has any issues with this one, please let me know. > I'm repeating myself a bit, but I'll try to articulate my only concern once again anyway. I run some tests on a couple of arm boxes and I didn't notice any regression or improvements for ondemand and conservative (FWIW this might also work as a tested-by), so I tend to take this series as a way to replace governor timers, making further cleanups and fixes possibile. I think you already confirmed this and I understand why you'd like this series to go in as I also think that what we have on top is beneficial. However, I still don't quite get why we want to introduce an interface for explicit passing of util and max if we are not using such parameters yet. Also, I couldn't find any indication of how such parameters will be used in the future. If what we need today is a periodic kick for cpufreq governors that need it, we should simply do how we already do for RT and DL, IMHO. Also because the places where the current hooks reside might not be the correct and useful one once we'll start using the utilization parameters. I could probably make a case for DL where we should place hooks in admission control path (or somewhere else when more sophisticated mechanisms we'll be in place) rather then in the periodic tick. > It has been in linux-next for a few days and seems to be doing well. > > As I said previously, there is a metric ton of cpufreq improvements > depending on it, so I'd rather not delay integrating it any more. > As said. I'm not against these changes since they open up to further substantial fixes. I'm only wondering if we are doing the right thing defining an interface that nobody is using and without an indication of how such thing we'll be used in the future. Best, - Juri