Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752095AbdGLN2d (ORCPT <rfc822;w@1wt.eu>);
        Wed, 12 Jul 2017 09:28:33 -0400
Received: from bombadil.infradead.org ([65.50.211.133]:51640 "EHLO
        bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751060AbdGLN2c (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 12 Jul 2017 09:28:32 -0400
Date: Wed, 12 Jul 2017 15:28:24 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Joel Fernandes <joelaf@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Patrick Bellasi <patrick.bellasi@arm.com>,
        Juri Lelli <juri.lelli@arm.com>,
        Andres Oportus <andresoportus@google.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Len Brown <lenb@kernel.org>, "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH RFC v4] cpufreq: schedutil: Make iowait boost more energy
 efficient
Message-ID: <20170712132824.mnoevjtm6wd6yh2c@hirez.programming.kicks-ass.net>
References: <20170709170826.29396-1-joelaf@google.com>
 <20170711101432.GB17115@vireshk-i7>
 <CAJWu+oqgN+1V4AF2QowT+fT_5SMQoNMy7NgrO8Zf3eSvAByTCg@mail.gmail.com>
 <20170712050035.GH17115@vireshk-i7>
 <20170712093630.lppm7yaqeiro2276@hirez.programming.kicks-ass.net>
 <20170712094623.GE1679@vireshk-i7>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170712094623.GE1679@vireshk-i7>
User-Agent: NeoMutt/20170609 (1.8.3)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1019
Lines: 20

On Wed, Jul 12, 2017 at 03:16:23PM +0530, Viresh Kumar wrote:

> No, I wasn't clear enough. Sorry about that. Lemme try again:
> 
> Suppose min freq is 500 MHz and Max is 2 GHz. The iowait-boost is
> set to 1 GHz right now (because of previous events with IOWAIT flag
> set), and sugov_set_iowait_boost() gets called again with IOWAIT flag,
> we boost the iowait-boost value to 2 GHz. We are in the rate_limit_us
> window right now, we return without changing the frequency.
> 
> If the next call into the schedutil governor happens due to normal
> util-update, flags will be passed as 0. With the current patch, we
> will bring iowait-boost back to 1 GHz (before updating the real
> frequency to 2 GHz) as the prev-iowait-boost boolean would be set.
> 
> And even if the task is periodically getting queued after IOWAIT,
> actual boosting may not happen at all in some cases.

Hmm, so you're worried about that ratelimit stuff? Shouldn't we fix that
independently -- IIRC Rafael proposed a max-filter over the window.