Re: [Xen-devel] Status of FLR in Xen 4.4

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Friday, September 27, 2013, 9:19:14 PM, you wrote:

> Hi Sander,

> thanks for the advice, I have actually no rcu stalls when i use the 
> no-cpuidle function. Do you have a little more insight on what is actually 
> causing this behaviour and if there is a better solution then this option, 
> cause I don't want to sacrifice my C-states (I would assume this makes the 
> overall server more power hungry?).

> Does this has something to do with the new tickless-kernel options in the 
> newer kernel, or is this really only an apci incompatibility with xen?

> Thanks!

 Are you running xen-unstable ?
 Some patches went in lately

 You also seem to have a motherboard with a AMD 890fx chipset, i suspect your 
bios also has issues around the HPET as mine had.
 I was also seeing RCU stalls on boot (and only on boot) .. hitting any key on 
the console when it appears to stall during boot made it continue in my case 
(happens several times).
 Took a while to find the problems, Jan Beulich has made and commited some 
patches that went in xen-unstable recently.

 Are you running xen-unstable ?
 If not, could you give it a try and provide the xl dmesg / serial log ?

 --
 Sander








>   2013/9/27 Sander Eikelenboom <linux@xxxxxxxxxxxxxx>

>   Hi Matthias,
>  
>  Have you tried adding "no-cpuidle" on the xen/hypervisor commandline in grub 
> ?
>  
>  --
>  Sander
>  

>  Friday, September 27, 2013, 7:07:33 PM, you wrote:
>  
 >> Hi Konrad,
>  
 >> good call! I was able to reproduce the error with the 3.12-rc2 kernel, got
 >> a lot of information with the new NMI traces (log attached), but since I'm
 >> not a xen hacker I don't really know how to continue from here. So I might
 >> add this to the original post and maybe someone can help me. After all the
 >> error persists for half a year now and besides 2 kernel version / .config
 >> Combinations (a 3.8.2 and a 3.6.something) I could never trace this issue
 >> back (even with bisecting the .config because at some point it seemed
 >> random).
>  
>  
 >> 2013/9/27 Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>  
 >>> On Thu, Sep 26, 2013 at 07:59:40PM +0200, Matthias wrote:
 >>> > I'm currently on a vanilla 3.8.2 kernel because this is the only >3.4
 >>> > kernel I found which doesn't give me this issue:
 >>> > http://lists.xen.org/archives/html/xen-users/2013-02/msg00114.html
 >>>
 >>> So v3.12 (or rather the latest and greaters of the Linus) has the mechanism
 >>> for the NMI - so you can actually see what is causing the stall.
 >>>
>  
>  



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