Re: trouble running FreeBSD with Xen-4.11 (including weird performance issues)

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

	hello.  Are you running these machines in hvm or pvh mode?  If hvm mode, are you seeing a
bunch of cpu taken up on dom0 by the qemu process supporting the hvm host?
Also, what is the xbd(4) problem you refer to?

-thanks
-Brian

On Mar 18,  4:47pm, "Greg A. Woods" wrote:
} Subject: Re: trouble running FreeBSD with Xen-4.11 (including weird perfor
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} So further to the apparent FreeBSD xbd(4) problems, I've also got a
} performance mystery.
} 
} I have to machines that are quite similar, but from slightly different
} hardware generations, a Dell R510, and a Dell PE2950.
} 
} They're both running NetBSD-current/amd64 9.99.81 with
} xenkernel411-4.11.4nb6 (though each built their own code).
} 
} I've copied the same FreeBSD 12.2-p4 kernel and ISO image files and
} xl.cfg file to each machine.
} 
} One (the R510) boots a domU and runs at what seems to be "normal" speed.
} This first machine is also running three other domUs.  Xl reports it
} using about 34s CPU time to get to the installer terminal type prompt.
} 
} The other (the PE2950) boots a domU that seems to spin in the FreeBSD
} kernel and chew up absolutely enormous amounts of time.  This server is
} running just the subject domU.  Xl says this one takes upwards of 1300
} seconds of CPU time to get to the terminal type prompt!  Hitting ^T
} during the startup (i.e. after /etc/rc starts) shows most of the time is
} spent in the kernel, e.g.:
} 
} load: 1.24  cmd: rcorder 32 [running] 12.58r 0.95u 9.35s 73% 1284k
} 
} The only difference in the console output on both has to do with the
} minor hardware, and especially CPU, differences.
} 
} 
} What the possible heck can be going on here!?!?!
} 
} How can I debug this?
} 
} 
} Also (and this is common to both systems, so is an underlying FreeBSD
} issue I guess) if I'm not careful what/when I type something to the
} installer (e.g. hit the right-arrow key at the wrong time) it seems to
} think it's done and hints are that the system tries to go multiuser, but
} it doesn't get very far before it comes to a grinding halt and will not
} respond at all (though it continues to use tiny amounts of CPU according
} to "xl list").
} 
} 	Updating motd: /etc/motd is not writable, update failed.
} 	Mounting late filesystems:.
} 	Updating /var/run/os-release done.
} 	Starting cron.
} 	Starting background file system checks in 60 seconds.
} 
} 	Thu Mar 18 22:49:32 UTC 2021
} 
} Sending a virtual NMI via "xl trigger fbsd-test nmi" will properly panic
} the system, but it doesn't actually do a nice kernel backtrace so I
} don't know where it's stuck:
} 
} 	timeout stopping cpus
} 	panic: NMI indicates hardware failure
} 	cpuid = 0
} 	time = 1616107272
} 	KDB: stack backtrace:
} 	Uptime: 12m40s
} 	Automatic reboot in 15 seconds - press a key on the console to abort
} 	--> Press a key on the console to reboot,
} 	--> or switch off the system now.
} 	Rebooting...
} 	cpu_reset: Stopping other CPUs
} 	timeout stopping cpus
} 	No known reset method worked, attempting CPU shutdown
} 
} --