linux-kernel - Re: [nohz] 2a16fc93d2c: kernel lockup on idle injection

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Message-ID: <20141216091528.17ee429d@ultegra>
Date:	Tue, 16 Dec 2014 09:15:28 -0800
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Pan, Jacob jun" <jacob.jun.pan@...el.com>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Wu, Fengguang" <fengguang.wu@...el.com>,
	Frederic Weisbecker <frederic@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, LKP <lkp@...org>,
	"Zijlstra, Peter" <peter.zijlstra@...el.com>
Subject: Re: [nohz] 2a16fc93d2c: kernel lockup on idle injection

On Tue, 16 Dec 2014 09:48:42 +0530
Viresh Kumar <viresh.kumar@...aro.org> wrote:

> On 16 December 2014 at 02:54, Pan, Jacob jun
> <jacob.jun.pan@...el.com> wrote:
> 
> > Looks good to me. You can add my Reviewed-by to the above patch.
> 
> Thanks.
> 
> > I have tested this fix and confirm powerclamp is working properly
> > now.
> 
> Oh, nice.
> 
> > However, we also have a planned patch for consolidated idle loop.
> > With this patch it causes some erratic behavior in idle injection.
> > I can’t seem to synchronize/align idle time around jiffies with
> > this patch + fix.
> >
> > Any suggestions welcome.
> > https://lkml.org/lkml/2014/6/4/56
> 
> And all works fine without this patch ?
well, there are other things i need to improve. but this patch
definitely causes some new unwanted behavior.
> 2a16fc93d2c9 ("nohz: Avoid tick's double reprogramming in highres
> mode")
> 
> I really don't know what stuff out of the two patches I posted (The
> above one and the fix I posted yesterday), will possible make the
> synchronization bad ..
> 
But since your patch has real benefits and does not cause regression
with the current code, there is no reason to hold it back. I was just
hoping to get help on debugging this.

thanks,

Jacob
> --
> viresh
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