Message-ID: <1440402888.3430.18.camel@gmail.com>
Subject: Re: [PATCH RESEND] sched/nohz: Affine unpinned timers to
 housekeepers
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Vatika Harlalka <vatikaharlalka@gmail.com>,
        Chris Metcalf <cmetcalf@ezchip.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Preeti U Murthy <preeti@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>
Date: Mon, 24 Aug 2015 09:54:48 +0200
In-Reply-To: <20150824074141.GA19209@gmail.com>
References: <1439516774-4614-1-git-send-email-fweisbec@gmail.com>
	 <20150823054032.GA28133@gmail.com>
	 <20150823160101.GA11078@linux.vnet.ibm.com>
	 <20150824064412.GA11581@gmail.com> <1440400997.3430.12.camel@gmail.com>
	 <20150824074141.GA19209@gmail.com>
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On Mon, 2015-08-24 at 09:41 +0200, Ingo Molnar wrote:
> * Mike Galbraith <umgwanakikbuti@gmail.com> wrote:
> 
> > On Mon, 2015-08-24 at 08:44 +0200, Ingo Molnar wrote:
> > 
> > > the 'housekeeping CPU' is essentially the boot CPU. Yet we dedicate a full mask to 
> > > it (housekeeping_mask - a variable mask to begin with) and recover the 
> > > housekeeping CPU via:
> > > 
> > > +       return cpumask_any_and(housekeeping_mask, cpu_online_mask);
> > 
> > There can be, and had better be if box is big, multiple housekeepers.
> 
> Yes - but that does not seem to be possible via the code right now AFAICS, so at 
> minimum it's incomplete.

In master housekeepers are set up in tick_nohz_init().  Everybody who's
not a nohz_full CPU is a housekeeper.

	-Mike

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