Date: Tue, 24 Jul 2018 18:12:30 -0400 From: Shawn Webb <shawn.webb@hardenedbsd.org> To: Alan Somers <asomers@freebsd.org> Cc: "freebsd-virtualization@freebsd.org" <virtualization@freebsd.org> Subject: Re: Overcommitting CPUs with BHyve? Message-ID: <20180724221230.tcljojufbwdl5ywy@mutt-hbsd> In-Reply-To: <CAOtMX2hEPnBaaKk25YWe6mYW-gCA6pGssEHTBB4GJ-C6sQU%2Btg@mail.gmail.com> References: <CAOtMX2hEPnBaaKk25YWe6mYW-gCA6pGssEHTBB4GJ-C6sQU%2Btg@mail.gmail.com>
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--fbaxk42dnpdw3af4 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jul 24, 2018 at 03:30:32PM -0600, Alan Somers wrote: > What are people's experiences with overcommitting CPUs in BHyve? I have = an > 8-core machine that often runs VMs totalling up to 5 allocated CPUs witho= ut > problems. But today I got greedy. I assigned 8 cores to one VM for a big > build job. Obviously, some of those were shared with the host. I also > assigned it 8GB of RAM (out of 16 total). Build performance fell through > the floor, even though the host was idle. Eventually I killed the build > and restarted it with a more modest 2 make jobs (but the VM still had 8 > cores). Performance improved. But eventually the system seemed to be > mostly hung, while I had a build job running on the host as well as in the > VM. I killed both build jobs, which resolved the hung processes. Then I > restarted the host's build alone, and my system completely hung, with > top(1) indicating that many processes were in the pfault state. >=20 > So my questions are: > 1) Is it a known problem to overcommit CPUs with BHyve? > 2) Could this be related to the pfault hang, even though the guest was id= le > at the time? VMWare's ESXi uses a special scheduler to do what it does. I wonder if it would be worthwhile to investigate implementing a scheduler in FreeBSD that provides decent performance for virtualized workloads. Thanks, --=20 Shawn Webb Cofounder and Security Engineer HardenedBSD Tor-ified Signal: +1 443-546-8752 Tor+XMPP+OTR: lattera@is.a.hacker.sx GPG Key ID: 0x6A84658F52456EEE GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89 3D9E 6A84 658F 5245 6EEE --fbaxk42dnpdw3af4 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEKrq2ve9q9Ia+iT2eaoRlj1JFbu4FAltXpEoACgkQaoRlj1JF bu7rLw/8DnZEhK1tcH+AlRwd3WlXtAeoSnTM8OLW0fR6jOOIYf6cS/+cxL0ALqca Pod0YLDY+rVMYKCZVxS7F8T5eTbiOxYBuaSM1lWKFr0wXaIxJ/EHm3S/Rodoag9Y 1BMtmo65FAN9jBoBjCXT6db3f/KfLKvHKDWtZrS6GdpQRtZPmIIPsmSAbp0wcKlv 0Dw71lyY23krOKx7OHq2ICrxSr6ewrYdnIHx6hQHWxKcpBqYsMbsH5VrXpi4IfWr G9uWGb44jDGxbFcGsLUW1mAAIdlTzgpyItBzcAEX9vZpF/1OKI6RK1BSD6AI7cEp ZKuRggDWjGKwaVafH0wXhm85QEk/okhRnU+KXqfJ5snaw/RiKuIs4mdjE1Kvv+hA /xDctlA5xr06X80rRSySf26XPmg4rbDuAyoHmgJsPCKU1Fx3UunT+4c21lHI0drm 5V4Buf3R2u2lLG/7Dc6Guqh4fDDOg65cfI7ZgSM6/FDgd/KjTa6AM9YgA18E+XdQ VOIDSyyZO5rKwNR5MD6InLheCGi+wIHWaPpj+jb7qYJOJZ7NPMKK2oJgpKQIMms4 VyiJQ4ZXb8e255PiiWH0EctuPVcNpvgR2Hj+Pgu57a1G/OB4TnLCDbp3hWh/Gfu9 tNv33XtE2SV6FTQIjxJi/YfCLT5UiCCMCEE8145PijxYHSlqSdg= =vfCa -----END PGP SIGNATURE----- --fbaxk42dnpdw3af4--
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