linux-kernel - Re: [PATCH v8 4/8] x86/sysctl: Add sysctl for ITMT scheduling feature

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Date:   Tue, 29 Nov 2016 09:30:49 -0800
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Borislav Petkov <bp@...e.de>
Cc:     rjw@...ysocki.net, tglx@...utronix.de, mingo@...hat.com,
        x86@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        peterz@...radead.org, jolsa@...hat.com,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v8 4/8] x86/sysctl: Add sysctl for ITMT scheduling
 feature

On Mon, 2016-11-28 at 09:56 +0100, Borislav Petkov wrote:
> On Tue, Nov 22, 2016 at 12:23:56PM -0800, Tim Chen wrote:
> > 
> > Intel Turbo Boost Max Technology 3.0 (ITMT) feature
> > allows some cores to be boosted to higher turbo
> > frequency than others.
> > 
> > Add /proc/sys/kernel/sched_itmt_enabled so operator
> > can enable/disable scheduling of tasks that favor cores
> > with higher turbo boost frequency potential.
> > 
> > By default, system that is ITMT capable and single
> > socket has this feature turned on.  It is more likely
> > to be lightly loaded and operates in Turbo range.
> > 
> > When there is a change in the ITMT scheduling operation
> > desired, a rebuild of the sched domain is initiated
> > so the scheduler can set up sched domains with appropriate
> > flag to enable/disable ITMT scheduling operations.
> > 
> > Co-developed-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > Co-developed-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> > Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
> > ---
> >  arch/x86/include/asm/topology.h |   7 ++-
> >  arch/x86/kernel/itmt.c          | 108 +++++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 112 insertions(+), 3 deletions(-)
> ...
> 
> > 
> > +/*
> > + * Boolean to control whether we want to move processes to cpu capable
> > + * of higher turbo frequency for cpus supporting Intel Turbo Boost Max
> > + * Technology 3.0.
> > + *
> > + * It can be set via /proc/sys/kernel/sched_itmt_enabled
> > + */sched_autogroup_enabled
> > +unsigned int __read_mostly sysctl_sched_itmt_enabled;
> Err, can we not have the boolean in the name itself?
> 
> I.e., have it called sysctl_sched_itmt and 1 means enabled and 0
> disabled? I.e., the classic thing. :)
> 
> Ditto for the sysctl name?

I am following the convention in /proc/sys/kernel/sched_autogroup_enabled
and sysctl_sched_autogroup_enabled that's also in /proc/sys/kernel.

Thanks.

Tim