Date: Tue, 7 Jul 2015 00:49:49 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Vatika Harlalka <vatikaharlalka@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>, preeti@linux.vnet.ibm.com,
        mingo@redhat.com, rafael.j.wysocki@intel.com, schwidefsky@de.ibm.com,
        paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, cl@linux.com,
        cmetcalf@ezchip.com, bitbucket@online.de
Subject: Re: [PATCH RESEND] nohz: Affining unpinned timers
Message-ID: <20150706224948.GF4981@lerouge>
References: <20150623083133.GA587@vatika-Inspiron-3443>
 <20150706165405.GD4981@lerouge>
 <alpine.DEB.2.11.1507061901580.3916@nanos>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.11.1507061901580.3916@nanos>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1510
Lines: 36

On Mon, Jul 06, 2015 at 07:18:22PM +0200, Thomas Gleixner wrote:
> On Mon, 6 Jul 2015, Frederic Weisbecker wrote:
> > I hope everybody received the patch because there is a ";" after each address :-)
> > 
> > On Tue, Jun 23, 2015 at 02:01:33PM +0530, Vatika Harlalka wrote:
> > > The problem addressed in this patch is about affining unpinned timers.
> > > Adaptive or Full Dynticks CPUs should not be disturbed by unnecessary
> > > jitter due to firing of such timers on them.
> > > This patch will affine timers to online CPUs which are not Full Dynticks
> > > in FULL_NOHZ configured systems. It will not bring about functional
> > > changes if NOHZ_FULL is not configured, because is_housekeeping_cpu()
> > > always returns true in CONFIG_NO_HZ_FULL=n.
> > > 
> > > Signed-off by: Vatika Harlalka <vatikaharlalka@gmail.com>
> > 
> > The patch looks good to me. Peter, Thomas, are you ok with it too?
> 
> By some definition of OK. The overhead of this is growing and growing.
> 
> We really need to make this a pull not a push model.

I'm currently working toward that.
See "[PATCH 0/8] tick/nohz: Tick dependency quick check + cleanups" as a
first step.

Now for this very patch, I don't know how we could make it better. Any
suggestion?

> Thanks,
> 
> 	tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/