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RE: [Xen-users] All domU blocked

To: "Rajat malhotra" <rajatmalhotra_1980@xxxxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] All domU blocked
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Tue, 12 Sep 2006 15:47:58 +0200
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From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Rajat malhotra
Sent: 12 September 2006 14:27
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] All domU blocked

> The only chance to see a domU in a state other than "b" is to use a SMP system. :)

 I have a smp and it shows blocked for me too Ernst! 
Being SMP doesn't guarantee that the guests are running when doing xm info. However, being uni-processor GUARANTEES that Dom0 is the one running...
"b" means that the guest is blocked, which is the state it is in when it's waiting for I/O, timers or other domain(s) to let it run again. It's impossible to say which one of those three (or more) possible causes are actually holding the process up. If you don't actively do something in a domain, it will be blocked. The best way to see SMP systems run is to put some infinite loop in a command shell, or better yet run an infinite loop in a compiled language, such as
int main(void)
   for(;;) ;  /* doesn't end */
   return 0;   /* this is just here to make the compiler happy */
gcc forever.c -o forever
That will make the domain use 100% of it's allocated CPU time (and any "spare" cpu-time too, if there is any).
Don't do this in Dom0, unless you want all DomU's to run very slow (and unless you have Credit scheduler, in which case it MAY work OK).


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