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Subject: Re: Debian 8 CPU stall
To: Rajil Saraswat <rajil.s@gmail.com>
References: <b011b080-5637-2da5-8a8a-819b7b1fabd3@gmail.com>
Cc: freebsd-virtualization@FreeBSD.org
From: Peter Grehan <grehan@freebsd.org>
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Date: Tue, 6 Dec 2016 20:50:46 -0800
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Hi Rajil,

> I get these messages in Debian 8 VM running in bhyve FreeBSD-11
> release.  Any idea what could be the issue:
>
> INFO: rcu_sched detected stalls on CPUs/tasks: {} (detected by 0,
> t=11047 jiffies, g=1038939, c=1038938, q=77)
> INFO: Stall ended before state dump start

  That's a sign that a vCPU wasn't able to run for an amount of time.

  Is the system oversubscribed ? i.e. more vCPUs than physical CPUs ? 
Or, is the guest performing a lot of i/o ?

later,

Peter.