linux-kernel - Re: [PATCH v2 2/3] cpufreq: acpi-cpufreq: add resolve

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20160531113815.GG9463@vireshk-i7>
Date:	Tue, 31 May 2016 17:08:15 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Steve Muckle <steve.muckle@...aro.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Juri Lelli <Juri.Lelli@....com>,
	Patrick Bellasi <patrick.bellasi@....com>,
	Michael Turquette <mturquette@...libre.com>
Subject: Re: [PATCH v2 2/3] cpufreq: acpi-cpufreq: add resolve_freq callback

On 30-05-16, 09:20, Steve Muckle wrote:
> A couple concerns... One is that if we do the lookup in
> cpufreq_driver_resolve_freq() for drivers which implement target_index()
> then it means using cpufreq_frequency_table_target() there.  This is a
> heavier weight function that can't take advantage of driver-specific
> knowledge that the freq table is sorted a particular way.

I completely agree.

> So for
> acpi-cpufreq we'd now be having to walk the whole table for every
> fast_switch.

I have just tried to address that with following set:

[PATCH 0/2] cpufreq: Use sorted frequency tables

Lets see what Rafael has to say about that.

> Another is that it'll be a a bit odd that the logic used to lookup the
> driver frequency will be different in the cached and uncached
> fast_switch cases. In the cached case it will have been determined by
> code in cpufreq_driver_resolve_freq() whereas in the uncached case it
> will be logic in the driver, in its fast_switch routine.

We can make both of them refer the above code then. Lets see.

-- 
viresh