Re: SwSusp to disk doesn't work - Try 2

[Thomas Meyer]

Thomas Gleixner schrieb:
> On Sun, 2007-03-11 at 22:09 +0100, Rafael J. Wysocki wrote:
>   
> > > > > > > >     update_sched_domains
> > > > > > > >      detach_destroy_domains
> > > > > > > >        [waits here] --> synchronize_sched (==synchronize_rcu)
> > > > > > > >         
> > > > > > > >                 
> > > > > > > Well, I think the call to wait_for_completion() does not return, probably
> > > > > > > because the task supposed to complete the completion is frozen at this
> > > > > > > point.  Can you please try to confirm that it gets stuck on
> > > > > > > wait_for_completion() in synchronize_rcu()?
> > > > > > >       
> > > > > > >               
> > > > > > Yes, it's in wait_for_completion() in synchronize_rcu().
> > > > > > As noted in some previous mail, it will wake up after
> > > > > > event - key press etc.
> > > > > >
> > > > > > Patch in http://lkml.org/lkml/2007/3/7/255 solves different problem.
> > > > > > I added it to my quilt and applied anyway -> no change.
> > > > > >     
> > > > > >             
> > > > > Does the problem go away if NO_HZ is unset?
> > > > >   
> > > > >           
> > > > i tried to boot with nohz=off, but the problem did persist.
> > > >         
> > > Hmmmm, both variants (nohz=off or recompiled kernel without NO_HZ) works for me.
> > >       
> > Definitely something strange is going on here.
> >
> > I think we need an advice from someone who knows the RCU internals.
> >     
>
> RCU synchronization depends on the timer interrupt. Which kernel version
> are you guys talking about ?
>
> 	tglx
>   

I talk about be521466feb3bb1cd89de82a2b1d080e9ebd3cb6 (2.6.21-rc3+).

The worst config is with nohz and without hrtimers: the kernel even 
doesn't come back after pressing the power key.

But i stay with without nohz and without hrtimers for now, because here 
the suspend to disk works.

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