Re: kvm guest: hrtimer: interrupt too slow

[Thomas Gleixner <tglx@linutronix.de>]

On Thu, 8 Oct 2009, Michael Tokarev wrote:
> Yesterday I was "lucky" enough to actually watch what's
> going on when the delay actually happens.
> 
> I run desktop environment on a kvm virtual machine here.
> The server is on diskless terminal, and the rest, incl.
> the window manager etc, is started from a VM.
> 
> And yesterday, during normal system load (nothing extra,
> and not idle either, and all the other guests were running
> under normal load too), I had a stall of everyhing on this
> X session for about 2..3, maybe 5 secounds.
> 
> It felt like completely stuck machine. Nothing were moving
> on the screen, no reaction to the keyboard etc.
> 
> And after several seconds it returned to normal.  With
> the familiar message in dmesg -- increasing hrtimer etc,
> to the next 50%.  (Without a patch from Marcelo at this
> time it shuold increase min_delta to a large number).
> 
> To summarize: there's something, well, more interesting
> going on here.  In addition to the scheduling issues that
> causes timers to be calculated on the "wrong" CPU etc as

Care to elaborate ?

Thanks,

	tglx