linux-kernel - Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45224055-7bf1-243b-9366-0f2d3442ef59@arm.com>
Date:   Tue, 11 Jul 2017 16:06:01 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Russell King - ARM Linux <linux@....linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Juri Lelli <juri.lelli@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant
 load-tracking support

On 11/07/17 07:01, Viresh Kumar wrote:
> On 10-07-17, 13:02, Dietmar Eggemann wrote:
>> Yes, I will change this. The #define approach is not really necessary
>> here since we're not in the scheduler hot-path and inlining is not
>> really required here.
> 
> It would be part of scheduler hot-path for the fast-switching case, isn't it ?
> (I am not arguing against using weak functions, just wanted to correct above
> statement).

Yes you're right here.

But in the meantime we're convinced that cpufreq_driver_fast_switch() is
not the right place to call arch_set_freq_scale() since for (future)
arm/arm64 fast-switch driver, the return value of
cpufreq_driver->fast_switch() does not give us the information that the
frequency value did actually change.

So we probably have to do this soemwhere in the cpufreq driver(s) to
support fast-switching until we have aperf/mperf like counters.