linux-kernel - Re: [PATCH 0/3] drivers: Frequency constraint infrastructure

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Message-ID: <20190130052752.v2zujifnkm3o7krf@vireshk-i7>
Date:   Wed, 30 Jan 2019 10:57:52 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "CAJZ5v0gtjq9Nh0WHbMzY+3Z3o5NWiWhP=QEXxzjVe3ta32z7=Q@...l.gmail.com" 
        <CAJZ5v0gtjq9Nh0WHbMzY+3Z3o5NWiWhP=QEXxzjVe3ta32z7=Q@...l.gmail.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Juri Lelli <juri.lelli@...il.com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Viresh Kumar <vireshk@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] drivers: Frequency constraint infrastructure

On 28-01-19, 14:04, Qais Yousef wrote:
> But we have no way to enforce this, no? I'm thinking if frequency can be
> constrained in PM QoS framework, then we will end up with some drivers that
> think it's a good idea to use it and potentially end up breaking this "should
> not work against schedutil and similar".
> 
> Or did I miss something?
> 
> My point is that if we introduce something too generic we might end up
> encouraging more users and end up with a complex set of rules/interactions and
> lose some determinism. But I could be reading too much into it :-)

People are free to use notifiers today as well and there is nobody
stopping them. A new framework/layer may actually make them more
accountable as we can easily record which all entities have requested
to impose a freq-limit on CPUs.

-- 
viresh