3.10.0: Full dynticks = high load

3.10.0: Full dynticks = high load

[Dâniel Fraga]

	I upgraded to kernel 3.10.0 and decided to try the new "Full
dynticks system (tickless)" option, but now the system load is always
at 1 or above.

	Using the previous "Idle dynticks system (tickless idle)" solves
the problem, so it seems the new Full dynticks code is causing this.

	Maybe Ingo Molnar can help to debug this (I put this in Power
Management, but if it should be in other area, please change).

My desktop is:
Asus P8Z68-V Pro/Gen3
Core i7 2700k
8GB RAM

	Feel free to suggest how can I debug this to help you. I can try
patches if you want.

	Thank you.

-- 
Linux 3.10.0: Unicycling Gorilla
http://www.youtube.com/DanielFragaBR
http://www.libertarios.org.br

Re: 3.10.0: Full dynticks = high load

[Heinz Diehl]

On 11.07.2013, Dâniel Fraga wrote: 

> 	I upgraded to kernel 3.10.0 and decided to try the new "Full
> dynticks system (tickless)" option, but now the system load is always
> at 1 or above.
> 
> 	Using the previous "Idle dynticks system (tickless idle)" solves
> the problem, so it seems the new Full dynticks code is causing this.
> 

This describes exactly what I have encountered, and "tickless idle"
fixed it for me, too. So I'll second that.

Re: 3.10.0: Full dynticks = high load

[Dâniel Fraga]

On Fri, 12 Jul 2013 08:52:27 +0200
Heinz Diehl <htd@fancy-poultry.org> wrote:

> This describes exactly what I have encountered, and "tickless idle"
> fixed it for me, too. So I'll second that.

	Thanks for the confirmation. I hope Ingo Molnar fixes it.

-- 
Linux 3.10.0: Unicycling Gorilla
http://www.youtube.com/DanielFragaBR
http://www.libertarios.org.br

Re: 3.10.0: Full dynticks = high load

[Mike Galbraith]

(add cc)

On Mon, 2013-07-15 at 10:05 -0300, Dâniel Fraga wrote: 
> On Fri, 12 Jul 2013 08:52:27 +0200
> Heinz Diehl <htd@fancy-poultry.org> wrote:
> 
> > This describes exactly what I have encountered, and "tickless idle"
> > fixed it for me, too. So I'll second that.
> 
> 	Thanks for the confirmation. I hope Ingo Molnar fixes it.
> 

Re: 3.10.0: Full dynticks = high load

[Frederic Weisbecker]

On Mon, Jul 15, 2013 at 03:36:46PM +0200, Mike Galbraith wrote:
> (add cc)
> 
> On Mon, 2013-07-15 at 10:05 -0300, Dâniel Fraga wrote: 
> > On Fri, 12 Jul 2013 08:52:27 +0200
> > Heinz Diehl <htd@fancy-poultry.org> wrote:
> > 
> > > This describes exactly what I have encountered, and "tickless idle"
> > > fixed it for me, too. So I'll second that.
> > 
> > 	Thanks for the confirmation. I hope Ingo Molnar fixes it.
> > 
> 
> 

Hi,

Sorry I'm missing the description of the issue. Could you please
repaste it?

Thanks!

Re: 3.10.0: Full dynticks = high load

[Dâniel Fraga]

On Mon, 15 Jul 2013 16:25:59 +0200
Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Hi,
> 
> Sorry I'm missing the description of the issue. Could you please
> repaste it?
> 
> Thanks!

	The problem is that when we use the new Full dynticks option
form kernel 3.10.0, the load will go high, always above 1. Bug?

-- 
Linux 3.10.0: Unicycling Gorilla
http://www.youtube.com/DanielFragaBR
http://www.libertarios.org.br

Re: 3.10.0: Full dynticks = high load

[Frederic Weisbecker]

On Mon, Jul 15, 2013 at 11:51:18AM -0300, Dâniel Fraga wrote:
> On Mon, 15 Jul 2013 16:25:59 +0200
> Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > Hi,
> > 
> > Sorry I'm missing the description of the issue. Could you please
> > repaste it?
> > 
> > Thanks!
> 
> 	The problem is that when we use the new Full dynticks option
> form kernel 3.10.0, the load will go high, always above 1. Bug?

You mean this is the result that the "uptime" command gives you? And
your system is doing something? Or is it mostly idle?

Re: 3.10.0: Full dynticks = high load

[Dâniel Fraga]

On Mon, 15 Jul 2013 17:01:35 +0200
Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Mon, Jul 15, 2013 at 11:51:18AM -0300, Dâniel Fraga wrote:
> > 	The problem is that when we use the new Full dynticks option
> > form kernel 3.10.0, the load will go high, always above 1. Bug?
> 
> You mean this is the result that the "uptime" command gives you? And
> your system is doing something? Or is it mostly idle?

	It is idle, but the load remains high all the time. Going back
to the "Idle dynticks system (tickless idle)" solves the problem.

	So the issue is with the new Full dynticks.

-- 
Linux 3.10.0: Unicycling Gorilla
http://www.youtube.com/DanielFragaBR
http://www.libertarios.org.br