Date: Thu, 24 Apr 2014 20:08:17 +0400 From: Roman Bogorodskiy <novel@FreeBSD.org> To: Peter Grehan <grehan@freebsd.org> Cc: freebsd-virtualization@FreeBSD.org Subject: Re: Understanding CPU and memory usage in Bhyve Message-ID: <20140424160816.GB3494@kloomba> In-Reply-To: <535557BC.8030300@freebsd.org> References: <20140421102138.GA6157@kloomba> <535557BC.8030300@freebsd.org>
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[-- Attachment #1 --] Peter Grehan wrote: > Hi Roman, > > > For the CPU, there's some info provided by bhyvectl, e.g.: > > > > /usr/sbin/bhyvectl --vm=bhyve --get-stats --cpu=1 > > > > in the field 'vcpu total runtime', for example: > > > > vcpu total runtime 8178870653 > > > > Two question about that: > > > > 1. What are the units used here? Looks like it's ticks, so if I want to > > convert this number, to, say, nanoseconds, would it be right to do > > something like: > > > > X * 1000**3 / kern.clockrate.stathz > > > > (X beeing the value returned by bhyvectl and kern.clockrate is a > > sysctl name)? > > It's in TSC units so you can convert to nsecs using the > machdep.tsc_freq sysctl node. > > > 2. This value shows only vcpu time, without hypervisor time? > > That's correct. To get the hypervisor and vCPU time together, you can > use existing CPU usage reporting (e.g. that used by top et al). Thanks for the clarification, it's very helpful. However, I need some more help with that. I'm trying to implement some domain stats reporting for the bhyve driver in libvirt and it looks like I choose a wrong approach initially. It's described here: https://www.redhat.com/archives/libvir-list/2014-April/msg00912.html But the summary is: is there a way to figure out how much CPU time bhyve and the guest spends on host CPUs N (N = 0, 1, ...)? > > For the memory stats, it's less obvious. Does guest always use an amount > > of memory specified at startup with '-m' (i.e. bhyve -m 1G) or it could > > use less? > > That's the maximum it can use. We currently don't expose the incore > amount from the vmspace representing the guest's physical - that should > be added to bhyvectl soon. Looking forward to that. > > What is the format of bhyvectl --get-{low,high}mem output? > > The number reported there isn't to do with guest usage, but how the > memory is divided between < 4G and above 4G. For example, the default > for bhyve is to use up to 3G below 4G, provide 1GB for PCI MMIO decode, > and then put the remainder of guest memory above 4G. Here's an example > for an 8G VM, with 3G of guest mem below 4G (starting address 0), and 5G > above 4G (starting address 4G): > > lowmem 0x0000000000000000/3221225472 > highmem 0x0000000100000000/5368709120 > > > PS I found it a little confusing that bhyvectl displays vcpu0 stats by > > default if --cpu is not provided, expected it provide info of all vcpus > > in the guest by default. > > Yes, that's a relic of the days when there was only a single vCPU > supported :( > > > Also, didn't find a way to get a number of vcpus in a running guest. > > Until the vCPU state is exposed by bhyvectl, or we provide a sysctl, > you can use heuristics: the number of vCPU threads for the bhyve > process, or scan all vCPUs and only count those that have a non-zero RIP. > > later, > > Peter. > Thanks, Roman Bogorodskiy [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (FreeBSD) iQEcBAEBAgAGBQJTWTbwAAoJEMltX/4IwiJqEygH/ippVMN8384c2RA8G8q2/jE1 LU2f4tyJaNQ/SMQtl3Ed0RTr8KThal2wXXGnujEw3TJaYTFDFaZ31rHAFT1/cPTG szuMgZ6mO47anNInoOBTQu0jOxgeUv/1z0V/zd+WDidFPRSI5YQFHeQe47/TjFqQ fJEUo6dExYeQl1tMkxi1oC1xvi04zbZgMuNPpeGUQBhpJ8MZkSILIEaiHWwFAOex g8hii/zHF9bEgNG/NnNPgrc56dIqn5kv736nLuWTHHog1pleTsW0qJL+X3IBIVZu CSKQ5twHMgWw57xXmpoMZwsIORkHb1AUHBHMZKbYA3WFKBNivrKB4x+6D5SR2S4= =ERSu -----END PGP SIGNATURE-----
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